Question 12

The service call lasted at least 3.5 hours.

For a plumbing company charging a flat fee of $60 plus $40 an hour, the customer’s total payment of at least $200 indicates that the service duration must be at least 3.5 hours.

A) at most 2 hours

If the service call lasted at most 2 hours, the total charge would be calculated as follows: $60 + (2 x $40) = $140. This amount is significantly less than the $200 paid by the customer, making this option incorrect.

B) at most 3.5 hours

Calculating for a maximum of 3.5 hours, the total charge would be $60 + (3.5 x $40) = $60 + $140 = $200. While this matches the minimum the customer remembered paying, it does not account for the possibility of the charge being higher, making this option less definitive than the correct choice.

C) at least 3.5 hours

This option is correct because if the service lasted at least 3.5 hours, the total charge would be $60 + (3.5 x $40) = $200, which aligns with the customer's minimum payment. Additionally, any time beyond 3.5 hours would increase the total cost, confirming that the service duration was at least this amount.

D) at least 2 hours

While the service could have been at least 2 hours, this option is not specific enough to address the customer’s total cost of at least $200. For instance, a service duration of exactly 2 hours would result in a total charge of $140, which is insufficient to meet the customer's payment, thus making this option incorrect.

Conclusion

The correct answer is that the plumbing service lasted at least 3.5 hours, as any duration shorter would not meet the customer’s total payment of at least $200. Options A and B do not fulfill the financial requirements established, while option D does not provide the necessary specificity to address the conditions of the payment. Thus, option C is the only correct description of the service duration.