Question

1. justin earned scores of 85, 92, and 95 on his science tests. what does he need to earn on his next science test so that the average (arithmetic mean) of the four exam scores is 93?

a. 93
b. 100
c. 85
d. 96

1. brads class collected 270 used books for the book drive. they packed them in boxes of 30 books each. how many boxes did they need?

a. 240
b. 10
c. 9
d. 5

1. joey participated in a dance - a - thon. his team started dancing at 10 a.m. on friday and stopped at 6 p.m. on saturday. how many hours did joeys team dance?

a. 52
b. 56
c. 30
d. 32

1. if one american dollar is worth 105 japanese yen, how many dollars is 945 yen worth?

a. 6 dollars
b. 9 dollars
c. 1,000 dollars
d. 99,225 dollars

1. callies grandmother pledged $0.85 for every mile callie walked in her walk - a - thon. callie walked 11 miles. how much money does her grandmother owe?

a. $9.35
b. $19.00
c. $10.00
d. $8.50

Explanation:

3.

Step1: Recall mean formula

The mean formula is $\text{Mean}=\frac{\text{Sum of all values}}{\text{Number of values}}$. Let the score on the next test be $x$. We have four scores in total, and the mean should be 93. So, $93=\frac{85 + 92+95+x}{4}$.

Step2: Cross - multiply

Multiply both sides of the equation by 4: $93\times4=85 + 92+95+x$.

Step3: Calculate left - hand side

$93\times4 = 372$.

Step4: Calculate sum of known scores

$85+92 + 95=272$.

Step5: Solve for $x$

$372=272+x$. Subtract 272 from both sides: $x=372 - 272=100$.

Step1: Use division formula

To find the number of boxes, we divide the total number of books by the number of books per box. Let $n$ be the number of boxes. Then $n=\frac{270}{30}$.

Step2: Calculate the result

$\frac{270}{30}=9$.

Step1: Calculate time on Friday

From 10 A.M. to 12 A.M. (mid - night) on Friday, there are $12 - 10=2$ hours. From 12 A.M. (mid - night) to 12 P.M. (noon) on Saturday, there are 12 hours. From 12 P.M. (noon) to 6 P.M. on Saturday, there are 6 hours.

Step2: Sum up the hours

The total number of hours is $2+12 + 6=30$ hours.

Answer:

b. 100

4.