AMC10 2010 A

AMC10 2010 A · Q8

AMC10 2010 A · Q8. It mainly tests Averages (mean), Arithmetic misc.

Tony works 2 hours a day and is paid \$0.50 per hour for each full year of his age. During a six month period Tony worked 50 days and earned \$630. How old was Tony at the end of the six month period?

Tony每天工作2小时，每满岁按年龄的每小时0.50美元付工资。在六个月期间，Tony工作了50天，赚了630美元。六个月期末Tony多大了？

(A) 9 9

(B) 11 11

(D) 13 13

(E) 14 14

Answer

Correct choice: (D)

正确答案：（D）

Solution

Answer (D): Tony worked for $2\cdot 50=100$ hours. His average earnings per hour during this period is $\frac{\$630}{100}=\$6.30$. Hence his average age during this period was $\frac{\$6.30}{\$0.50}=12.6$, and so at the end of the six month period he was 13.

答案（D）：托尼工作了 $2\cdot 50=100$ 小时。在此期间他每小时的平均收入为 $\frac{\$630}{100}=\$6.30$。因此，他在这段时间内的平均年龄为 $\frac{\$6.30}{\$0.50}=12.6$，所以在六个月结束时他是 13 岁。

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