Pre-Test Question:

Chapter 3. Chapter 3 Average and Median

Math and Graphing Review
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You must read each slide, and complete any questions on the slide, in sequence.

Imagine you have five nieces and nephews and their ages are: 4, 10, 8,9, and 15. The average age of your nieces and nephews is _______,while their median age is _______.

A.
B.
C.
D.

Correct! The average is 9.2 and the median is 9.
Sorry,the average is 9.2 and the median is 9. To calculate the average we add all the numbers together: 4 + 10 + 8 + 9 + 15 = 46 and then divide by the number of items we have (five): 46/5 = 9.2. To calculate the median, we arrange the numbers from lowest to highest and find the middle-most value, in this case, 9.

1.

Suppose Mike, Roberta,and Paul all go out to dinner. Mike’s meal costs $27, Roberta’s costs $38, and Paul’s costs $28. Assuming this already includes any tip, what is the average cost of their dinners? (Hint: This is also the amount each would pay if splitting the bill equally!)

The average cost of their dinners is:

A.
B.
C.
D.

Correct! The average cost of their dinners is $31.
Sorry,the average cost of their dinners is $38. To calculate the average we add up the cost of each meal: 27 + 38 + 28 = 93. We then divide this total cost by three (the number of people) and get 93/3 = $31.

2.

Suppose you ask your three friends how many cups of coffee they each drink each week. They report the following: 3 cups, 6 cups, and 18 cups. What is the average number of cups your friends drink each week? What is the median?

A.
B.
C.
D.

Correct! The average is 9 and the median is 6.
Sorry, the average is 9 and the median is 6. To calculate the average we add all the numbers together: 3 + 6 + 18 = 27. Then we divide by the number of items we have (three): 27/3 = 9. To calculate the median we arrange the numbers from lowest to highest and find the middle-most value, in this case 6.

3.

Suppose you go to four stores to purchase some socks. In the first store the socks cost $10.50, in the second they cost $8.00, in the third $6.00, and in the fourth $4.19. What is the median price of socks across the four stores?

A.
B.
C.
D.

Correct! The median price is $7.00.
Sorry, the median price is $7.00. With an even number of elements we calculate the median by taking the average of the two middle-most values:(6.00+8.00)/2=$7.00.

4.

Calculate the average and median of the following numbers:

18, 1, 5, 6, 12, 13, 8

The average of these numbers is _________ and the median is _________:

A.
B.
C.
D.

Correct! The average is 9 and the median is 8.
Sorry, the average is 9 and the median is 8. To calculate the average we add all the numbers together: 18 + 1 + 5 + 6 + 12 + 13 + 8 = 63 and then divide by the number of items we have (seven): 63/7 = 9. To calculate the median we arrange the numbers from lowest to highest and find the middle-most value, in this case 8.

5.

Suppose you take a survey among a group of people, asking them how much they paid for their shoes. Five report paying $100, three report paying $75, and two report paying $50. What is the average price paid for shoes?

A.
B.
C.
D.

Correct! The average price paid is $82.50.
Sorry, the average price paid is $82.50. To calculate the average price paid we first calculate the total paid: 5 × 100 + 3 × 75 + 2 ×50 = $825. We then divide the total amount paid by the number of people (10): $825/10 = $82.50.