AMC8 2014

AMC8 2014 · Q3

AMC8 2014 · Q3. It mainly tests Averages (mean).

Isabella had a week to read a book for a school assignment. She read an average of $36$ pages per day for the first three days and an average of $44$ pages per day for the next three days. She then finished the book by reading $10$ pages on the last day. How many pages were in the book?

Isabella 有一周时间阅读一本书以完成学校作业。她在前三天平均每天读了 $36$ 页，接下来的三天平均每天读了 $44$ 页。最后一天她读了 $10$ 页，完成了这本书。请问这本书共有多少页？

(A) 240 240

(B) 250 250

(D) 270 270

(E) 280 280

Answer

Correct choice: (B)

正确答案：（B）

Solution

Isabella read $3\cdot 36+3\cdot 44$ pages in the first 6 days. Although this can be calculated directly, it is simpler to calculate it as $3\cdot (36+44)=3\cdot 80$, which gives that she read $240$ pages. On her last day, she read $10$ more pages for a total of $240+10=\boxed{\textbf{(B)}~250}$ pages.

Isabella 在头六天共读了 $3 \cdot 36 + 3 \cdot 44$ 页。虽然可以直接计算，但更简单的方式是计算 $3 \cdot (36 + 44) = 3 \cdot 80$，得出她读了 $240$ 页。最后一天她又读了 $10$ 页，总共读了 $240 + 10 = \boxed{\textbf{(B)}~250}$ 页。

Topics

AR.006 Averages (mean)