Question

5 multiple choice 3 points
if the average of five numbers is 20, and four of the numbers are 15, 25, 10, and 30, what is the fifth number?
20
10
15
25

Explanation:

Step1: Find total sum of 5 numbers

Total sum = Average × Number of values = $20 \times 5 = 100$

Step2: Sum the 4 known numbers

Sum of 4 numbers = $15 + 25 + 10 + 30 = 80$

Step3: Calculate the fifth number

Fifth number = Total sum - Sum of 4 numbers = $100 - 80 = 20$

Answer:

20