Suppose that Helen buys three items for 47 cents each, five items for 71 cents each, and two items for 1.21 each. What was the average cost of all the items she bought?
Would the answer be 74 cents?
Right.
To calculate the average cost of all the items Helen bought, we need to find the total cost and divide it by the total number of items.
Let's calculate the total cost:
- Helen bought 3 items for 47 cents each, so the cost of these items is 3 * 47 cents = 141 cents.
- She also bought 5 items for 71 cents each, so the cost of these items is 5 * 71 cents = 355 cents.
- Finally, she bought 2 items for 1.21 each, so the cost of these items is 2 * 1.21 = 2.42 dollars (or 242 cents).
Now, we can find the total cost by adding up the costs of all the items:
141 cents + 355 cents + 242 cents = 738 cents.
Hence, the total cost of all the items Helen bought is 738 cents.
To find the average cost, we divide the total cost by the total number of items. Helen bought a total of 3 + 5 + 2 = 10 items.
Therefore, the average cost of all the items is 738 cents รท 10 items = 73.8 cents or rounded to the nearest cent, 74 cents.
So the correct answer is 74 cents.