题目

You can rent DVDs at a local video store for $5.00 per movie without a membership. However, if you purchase a membership for $7.00 per month, you can rent DVDs for $2.00 a piece. What is the minimum amount of DVDs you would have to rent to make it worth it to purchase the membership.

选项

A.

1

B.

2

C.

3

D.

4

E.

5

解析

假设租\(x\)张DVD时达到收支平衡: - 不办会员租\(x\)张DVD的费用 = \(5x\) - 办会员租\(x\)张DVD的费用 = \(7 + 2x\) 此时满足\(7 + 2x ≤ 5x\),推导得: \[ 3x ≥ 7 \] \[ x ≥ 2.3 \] 因此\(x\)的最小值为3。 答案:选项C
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