Question

Art 的饼干每块卖 $60$ ¢。为了从一批面团中赚到同样金额，Roger 的一块饼干应卖多少钱？

Art's cookies sell for $60$ ¢ each. To earn the same amount from a single batch, how much should one of Roger's cookies cost?

$18$ ¢

$25$ ¢

$40$ ¢

$75$ ¢

$90$ ¢

Art 做 $12$ 块饼干，每块卖 $60$ 分，所以一批收入 $12\cdot60=720$ 分。

这批面团面积为 $12\cdot12=144$ 平方英寸，每块 Roger 饼干面积为 $4\cdot2=8$ 。因此 Roger 能做 $144\div8=18$ 块饼干。

若要用 $18$ 块饼干赚 $720$ 分，每块 Roger 饼干应卖 $720\div18=40$ 分。

所以正确答案是 C。

Art makes $12$ cookies that sell for $60$ cents each, so one batch earns $12\cdot60=720$ cents.

The batch has $12\cdot12=144$ square inches of dough area, and each Roger cookie has area $4\cdot2=8$ . Thus Roger makes $144\div8=18$ cookies.

To earn $720$ cents from $18$ cookies, each Roger cookie should cost $720\div18=40$ cents.

Thus, C is the correct answer.