write an expression 13+ 19+ 17 using mental math

Answers

Answer 1

Explanation:

It is convenient to regroup the numbers, and adjust two of them to "make a ten".

  = 13 + 17 + 19 . . . . rearrange (swap the order of 17 and 19)

  = (10 + 3) + (-3 + 20) + 19 . . . . "make a ten" by adding or subtracting a small number. Here, those adjustments cancel—which is the point of doing it.

  = 10 + 20 + 19

  = 30 + 19

  = 49


Related Questions

will give BRAINEST

Solve the system of equations below by graphing both equations with a pencil and paper. What is the solution?

Answers

y = x + 1
y = 1/2x + 3

x + 1 = 1/2x + 3
x - 1/2x = 3 - 1
1/2x = 2
x = 2 / (1/2)
x = 2 * 2/1
x = 4

y = x + 1
y = 4 + 1
y = 5

so ur solution is : (4,5)

What is the value of n?

9×27+2×31-28= n

Answers

Hey, there! 

[tex]9(27) + 2(31) = n \\ \\ 9(27) = 243 \\ \\ 2(31) = 62 \\ \\ 28 = -28 \\ \\ \\ 243 + 62 + (-28) = n \\ \\ n = 277 [/tex]

Good luck on your assignment and enjoy your day 

~[tex]MeIsKaitlyn:)[/tex]

n=277

Hope this will help!

(b) we often read that iq scores for large populations are centered at 100. what percent of these 78 students have scores above 100? (round your answer to one decimal place.)

Answers

Given that the iq scores for large populations are centered at 100.

To get what percent of these 78 students have scores above 100 we conduct a normal distribution probability of the data.

P(x > 100) = P(z > (100 - 100)/sd) = P(z > 0) = 1 - P(z < 0) = 1 - 0.5 = 0.5 = 50%

a triangle with a base of 12 millimeters and height of 11 millimeters

Answers

Perimeter= 34
Area= 132

Give the derivative of f(x) = arctan(e^(5x)) at the point where x=0

Answers

[tex]f(x)=\arctan e^{5x}[/tex]
[tex]f'(x)=\dfrac{(e^{5x})'}{1+(e^{5x})^2}=\dfrac{5e^{5x}}{1+e^{10x}}[/tex]
[tex]f'(0)=\dfrac5{1+1}=\dfrac52[/tex]
Final answer:

The derivative of f(x) = arctan(e^(5x)) at x=0 is 2.5, using chain rule and the derivative of the arctan function.

Explanation:

The function given is f(x) = arctan(e^(5x)). To find its derivative at the point where x=0, we have to use the chain rule and the derivative of the arctan function.

Firstly, the derivative of arctan(u) is 1 / (1 + u^2). Therefore, if u = e^(5x), then the derivative of arctan(e^(5x)) is: 1 / (1 + (e^(5x))^2).

Secondly, because u = e^(5x), the derivative of u is 5e^(5x). We incorporate this using the chain rule to get the derivative: 5e^(5x) / (1 + (e^(5x))^2).

Finally, substitute x=0 into the derivative equation. We find that the derivative of the function at x=0 is: 5 / (1 + 1) = 2.5.

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7x2+3[81-(4x6)]
Simplify

Answers

7x2+3[81-24]
7x2+3-57
14+3-57
17-57
-40

I really need help on this

Answers

First of all, the cubed root of 216 is 6, so that leaves you with two answers, A or B. The answer is B. 
The answer is B: 6x^9

14+3n=8n-3(n-4) this is really hard please help me

Answers

14+3n=8n-3(n-4)
distribute
14+3n=8n-3n+12
add like terms
14+3n=5n+12
subtract 3n from both sides
14=2n+12
subtract 12 from both sides
2=2n
divide both sides by 2
n=1
Hope this helps!!

Which one of the following statements about quadrilaterals is true?

A.) A quadrilateral with only one set of parallel sides is a square.
B.) A quadrilateral with a right angle is a rhombus.
C.) A quadrilateral with two pairs of parallel sides is a trapezoid.
D.) A parallelogram with a right angle is a rectangle.

Answers

I dont know if this is going to help any but I think the correct answer is D- A parallelogram with a right angle is a rectangle.
Sorry if this does not help.
Have a nice day.

Answer:its c

Step-by-step explanation:

I got the answer wrong and the right answer was c so there yall

A concrete walk of uniform width is to be laid around a rectangular flower bed that is 60 feet long and 30 feet wide. If the area of the walk is to be 279 square feet, what is the width of the walk?

Answers

We know that the area of the flower bed is 60 x 30 = 1800 sqft and that the area of the walk is 279 sqft. We will make an equation that represents the two areas added together so we must add 2x to 30 ft and 2x to 60 ft to include the width of the walk that is of equal width all around that is the 2x. So we get,
(30 + 2x)(60 + 2x)= 279 + 1800 then we simplify to 4x^2 +180x-279=0, factor to (2x-3)(2x+93)=0. Now we solve for x. 2x-3=0 gives us x=1.5 and 2x-93=0 gives us -93/2 which is negative and we know distance is positive so that solution is omitted. We get that the width around the flower garden is 1.5 ft.

In Christopher Marlowe's The Tragical History of Doctor Faustus, why did Faustus begin to believe that human salvation was impossible? Faustus first began to believe that human salvation was impossible because In addition, he had

Answers

In Christopher Marlowe's The Tragical History of Doctor Faustus, Faustus began to believe that human salvation was impossible because he read the scripture and saw that all human beings sin and are doomed. He thought that this meant that no matter how you lived your life, and how much you tried to be a good person, in the end you would still sin and thus God won't forgive you. This is why he consciously gave in to sin. 

In addition, he had been misled by Mephastophills, who caused him to misread the scriptures. Mephastophills is the Devil, and obviously the Devil won't tell the truth because he wants to collect more souls to torture in his realm. Faustus fell for his tricks and was mislead to misinterpret the scriptures, which lead to him losing his soul ultimately. 

Answer:

he read the scripture and saw that all human beings sin and are doomed

Step-by-step explanation:

What is .0091 rounded to thousands?

Answers

.009 is the correct answer

Another tent has the perimeter of 7.2 metres. If the width is 1.3 metres, what is the length?

Answers

P = 2( L + W)
P = 7.2
W = 1.3

7.2 = 2(1.3 + L)
7.2 = 2.6 + 2L
7.2 - 2.6 = 2L
4.6 = 2L
4.6/2 = L
2.3 = L <== length is 2.3 m 

Answer:  Length of tent would be 2.3 meters.

Step-by-step explanation:

Since we have given that

Perimeter of tent = 7.2 meters

Width of tent = 1.3 meters

Since we have given that

Perimeter = 2( length + width)

[tex]7.2=2(Length+1.3)\\\\\dfrac{7.2}{2}=Length+1.3\\\\3.6=Length+1.3\\\\3.6-1.3=Length\\\\2.3\ m=Length[/tex]

Hence, Length of tent would be 2.3 meters.

A small piece of metal weighs 0.77 gram. What is the value of the digit in the tenths place

Answers

70 hundredths of a gram
0.7 is the value hope this helps

Why is it helpful to write a number as a product of primes?

Answers

Because it helps in reducing fractions to their simplest terms and finding the lowest common denominator when adding or subtracting fractions. 
With least prime factorization, You can find things like the GCF

what is the equation of the line in slope intercept form m=2/7 and the y intercept is (0,-12)
A y=2/7x +12
B y=2/7x -12
C y=13x-2/7
D y=12x +2/7

Answers

B is your answer! All you do for this equation is go oh look m=2/7 well this means y=2/7x and you have a -12 so than you just plug it in. To get y=2/7x-12


How many gallons of 20% antifreeze should be mixed with 10 gallons of 92% antifreeze to obtain a 65% antifreeze mixture?

Answers

Add G gallons.
10*92 + G*20 = (10+G)*65

​1/5 of the animals at a zoo are monkeys. 5/7 of the monkeys are male. What fraction of the animals at the zoo are male monkeys?

Answers

I think it is 1/7 I hope this helps

Answer : The fraction of the animals at the zoo are male monkeys, [tex]\frac{1}{7}[/tex]

Step-by-step explanation :

As we are given that:

Fraction of animals at a zoo are monkeys = [tex]\frac{1}{5}[/tex]

Fraction of monkeys are male = [tex]\frac{5}{7}[/tex]

So,

Fraction of the animals at the zoo are male monkeys = Fraction of animals at a zoo are monkeys × Fraction of monkeys are male

Fraction of the animals at the zoo are male monkeys = [tex]\frac{1}{5}\times \frac{5}{7}[/tex]

Fraction of the animals at the zoo are male monkeys = [tex]\frac{1}{7}[/tex]

Thus, the fraction of the animals at the zoo are male monkeys, [tex]\frac{1}{7}[/tex]

5n=35 what is n equal to?

Answers

Salutations!

5n=35 what is n equal to?

5n = 35

Isolate the number 5, why? because all the variables should be aside, also, we are finding the "n".

n = 32/5

n = 5.

N equals to 5.

Hope I helped (:

Have a great day!

Zach is 3 years older than twice his sister Michelle's age. Let m represent Michelle's age. Write an expression in terms of m to represent Zach's age.

Answers

zach is 3 yrs older then twice his sister (m)

zack is : 2m + 3
2m+3 is the answer to that

Evaluate the expression for the given values.

mx−y when m=1, x=5x=5, and y=2

Enter your answer in the box.


Answers

Step 1) Start with the original expression

Step 2) Replace m with 1 (since m = 1)

Step 3) Replace x with 5 (since x = 5)

Step 4) Replace y with 2 (since y = 2). After this step we use PEMDAS to evaluate.

Step 5) Multiply (the M in PEMDAS)

Step 6) Subtract (the S in PEMDAS). Note how the S comes after the M. So subtraction is done after multiplication.

----------------------------------------------------------------

Step 1) m*x - y 

Step 2) 1*x - y

Step 3) 1*5 - y

Step 4) 1*5 - 2

Step 5) 5 - 2

Step 6) 3

----------------------------------------------------------------

So the final answer is 3

Ray
OC
divides ∠AOB into two angles. Find the measurement of ∠AOC, if m∠AOB = 155°, and m∠AOC is by 15° greater than m∠COB.

Answers

We are given that:

m∠AOB = m∠AOC + m∠COB

We are also given that:

m∠AOC = m∠COB + 15

m∠AOB = 155

Therefore:

155 = m∠COB + 15 + m∠COB

2 m∠COB = 140

m∠COB = 70°

and,

m∠AOC = m∠COB + 15 = 85°

 

Answers:

m∠COB = 70°

m∠AOC = 85°

Write the equation in standard form of the circle with radius 5 and center 0,3

Answers

The equation of a circle is (x-h)²+(y-k)²=r², with h being the x value in the center, k being the y value, and r being the radius. x and y can stay variables, so we can plug numbers in to get (x-0)²+(y-3)²=5²=25=x²+(y-3)²

What is the answer to 4+(-1 2/3)

Answers

4 - 1 2/3

12/3 - 5/3 = 7/3

7/3 is your answer

hope this helps

Let y be a random variable with p(y) given in the accompanying table. find e(y ), e(1/y ), e(y 2 − 1), and v(y ). y 1 2 3 4 p(y) .4 .3 .2 .1

Answers

Final answer:

This answer pertains to the computation of expected and variance values for a discrete random variable y using its given probability distribution function. Relevant principles include multiplying each value of y with its corresponding probability and then summing the products for the expected value, and further operations for other expected values and variance.

Explanation:

The subject pertains to finding the expected and variance values of a discrete random variable y, based on its probability distribution function (PDF). In this case, we have four values for y (i.e., 1, 2, 3, and 4) with corresponding probabilities given as .4, .3, .2, and .1 respectively.

E(y) or the expected value of y is obtained by multiplying each value of y with its corresponding probability and then summing the products, according to the formula E(y) = Σ y*P(y).

e(1/y) is the expected value of the reciprocal of y, obtained similarly by multiplying each 1/y with its corresponding P(y) and summing up the products.

e(y 2 − 1) represents the expected value of y-squared minus one, obtained by squaring each y, subtracting one, multiplying with the corresponding P(y), and then adding the results.

Finally, for v(y) or the variance of y, one would first need to find the expected value of y-squared [E(y^2)], and then use the identity v(y) = E(y^2) - {E(y)}^2 to compute the variance.

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What proportion of a normal distribution is located between z = 0 and z = +1.50?​ ​0.4332 ​0.8664 ​0.0668 ​0.9332?

Answers

0.4332 The problem is asking what proportion of a normal distribution is within 1.50 standard deviations on the positive half of the curve. So let's take a look. First thing is to figure out what would be a reasonable answer. Looking at the standard deviation, there will be 34.1% within 0 to +1 standard deviations. And there will be 47.7% within 2 standard deviations. So the correct answer will be something between 0.341 and 0.477. So let's look at the possible answers. ​0.4332 - This answer falls within the desired range. It's a candidate. ​0.8664 - This answer is way too large. Well over 50%, so it can't work. ​0.0668 - This answer is way too small. So once again, it can't work ​0.9332 - If the 0.8664 above was too large, imagine how unreasonable this answer is. Also wrong. So of the 4 available choices, only 0.4332 is possible. So that's the correct answer.

Solve the system by substitution . 2x+y=-11 3x-4y=11
(3,5)
(-5,-3)
(-3,-5)
(5,3)

Answers

2x + y = -11
y = -2x - 11

3x - 4y = 11
3x - 4(-2x - 11) = 11
3x + 8x + 44 = 11
11x = 11 - 44
11x = - 33
x = -33/11
x = -3

y = -2x - 11
y = -2(-3) - 11
y = 6 - 11
y = - 5

solution is (-3,-5) <==

3) Linda started taking piano lessons. She had to practice 1 3/4 hours each day. If after only 8 days Linda decided she wanted to stop, how many hours did she take lessons?

Answers

since 1 3/4 hours is equal to 105 minutes and since she did that amount each day and she practiced for eight days. You would multiply 105 times 8 to get 840 minutes but converted to hours would be 14 hours.

Gary made 20 treat bags for his Halloween party. In every 3rd bag he put lollipops, in every 4th bag he put Hershey Kisses and in every 5th bag he put fake eyeballs. How many of the 20 bags have all three items in them? ( By the way this is an LCM problem. I need help asap plz.)

Answers


3 - 6 - 9 - 12 - 15 - 18 - 21 - 24 - 27 - 30 - 33 - 36 - 39 - 42 - 45 - 48 - 51 - 54 - 57 - 60

4 - 8 - 12 - 16 - 20 - 24 - 28 - 32 - 36 - 40 - 44 - 48 - 52 - 56 - 60

5 - 10 - 15 - 20 - 25 - 30 - 35 - 40 - 45 - 50 - 55 - 60

SOOOO that means the LCD is 60 c:

( Basically, to find the LCD all you gotta do is count by whichever number is the denominator until they match, in this case, it was 60 )

You can do the rest :D

In a certain town, 22% of voters favor a given ballot measure. for groups of 21 voters, find the variance for the number who favor the measure.
a. 1.9
b. 13
c. 4.6
d. 3.6

Answers

Final answer:

The variance for the number of voters who favor the ballot measure in groups of 21 is calculated using the formula for a binomial distribution, which yields an answer of 3.78. The closest option to this value is 3.6, answer option d.

Explanation:

In the question about a town where 22% of voters favor a given ballot measure, we are asked to find the variance for the number of voters who favor the measure in groups of 21 voters. To calculate the variance, we use the formula for the variance of a binomial distribution, which is np(1-p), where 'n' is the number of trials (voters in this case), 'p' is the probability of a voter favoring the measure, and '1-p' is the probability of a voter not favoring the measure.

Using the information provided:

n = 21 (the number of voters in a group)p = 0.22 (the probability of a voter favoring the measure)

Thus, the variance (Var) is:

Var = np(1-p) = 21 × 0.22 × (1 - 0.22) = 21 × 0.22 × 0.78 = 3.78

The closest answer to 3.78 is 3.6, which is option d.

Variance formula: [tex]\(npq\)[/tex]. Substitute [tex]\(n = 21\), \(p = 0.22\), \(q = 0.78\)[/tex]. Calculate to get variance. Answer: d. 3.6

To find the variance for the number who favor the measure in groups of 21 voters, we can use the binomial distribution formula.

The variance of a binomial distribution is given by [tex]\(npq\)[/tex], where:

- [tex]\(n\)[/tex] is the number of trials (number of voters in each group),

- [tex]\(p\)[/tex] is the probability of success (proportion of voters favoring the measure), and

- [tex]\(q\)[/tex] is the probability of failure (proportion of voters not favoring the measure).

Given:

- [tex]\(n = 21\)[/tex],

- [tex]\(p = 0.22\)[/tex] (22% favor the measure), and

- [tex]\(q = 1 - p = 1 - 0.22 = 0.78\)[/tex],

Let's calculate the variance:

[tex]\[ \text{Variance} = npq = 21 \times 0.22 \times 0.78 \][/tex]

[tex]\[ \text{Variance} = 21 \times 0.1716 \][/tex]

[tex]\[ \text{Variance} = 3.5976 \][/tex]

Rounded to one decimal place, the variance is approximately [tex]\(3.6\)[/tex].

So, the correct answer is d. 3.6.

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