Averages- Finding Unknown Values
** Mean = Average
Example: The average of 5 numbers is 13. Four of the numbers are 11, 9, 15 and 26.
Step 1: Multiply- 13 x 5 = 65
Step 2: Add - 11+ 9+ 15 + 26 = 61
Step 3: Subtract - 65 -61 = 4
1. The average of 4 numbers is 20. Three of the numbers are 12, 18 and 28. Find the fourth number.
2. The average of 3 amounts of money is $7.05. Two of the amounts are $1.96 and $4.58. Find the third amount.
3. The mean of 5 numbers is 20. Four of the numbers are 16, 9, 27 and 36. What is the fifth number?
4. The average of 6 measurements is 8.40m. Five of the measuements are 4.36m, 7.25m, 6.10m, 9.74m and 11.35m. Find the sixth measurement.
5. Sunil wants to earn 88% in her Chemistry class. She has one quiz left to take. On the first 5 quizzes, she received a 74%, 92%, 83%, 98%, 100%. What must she score on the 5th quiz to get the 88% she wants?
6. After working 5 days, an employee earned a mean of $520. On four of those days, he earned $600, $345, $440 and $500. How much did he earn on the fifth day?
7. Kelly collected an average of 50 stamps after 4 weeks. In week one she collected 60 stamps and in week 2 she only collected two-thirds of this amount. In week 3, she collected 80 stamps. How many stamps did she collect in week 4?
8. The mean weight of five complete computer stations is 167.2 pounds. The weights of four of the computer stations are 158.4 pounds, 162.8 pounds, 165 pounds, and 178.2 pounds respectively. What is the weight of the fifth computer station?
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