Question

Bridget 在杂货店买了一袋苹果。她把一半苹果给了 Ann。然后她给了 Cassie $3$ 个苹果，自己留下 $4$ 个苹果。Bridget 买了多少个苹果？

Bridget bought a bag of apples at the grocery store. She gave half of the apples to Ann. Then she gave Cassie $3$ apples, keeping $4$ apples for herself. How many apples did Bridget buy?

$3$

$4$

$7$

$11$

$14$

答案：E

知识点：逆推法

难度评级：370

解答：

可以倒推，从 Bridget 自己留下的 $4$ 个苹果开始。加上她给 Cassie 的 $3$ 个苹果，这一半共有 $7$ 个苹果。

因为她把原来苹果的一半给了 Ann，所以再乘以 $2$ 。 $7 \cdot 2 = 14$ ，因此 Bridget 一开始有 $14$ 个苹果。

所以正确答案是 E。

We can work backwards, starting with the $4$ apples that Bridget kept for herself. Adding the $3$ apples that she gave Cassie, she now has $7$ apples.

Finally, we multiply this value by $2$ since she gave half of her initial apples to Ann. $7 \cdot 2 = 14,$ so Bridget started off with $14$ apples.

Thus, E is the correct answer.

2009 AMC 8 第 1 题

答案：E

难度评级：370

解答：

其他年份的第 1 题