Question

Carl is taking a math test. There are 10 questions which take 30 seconds each; 15 questions which take 40 seconds each; and 12 questions which take two minutes each. Carl pauses for 5 seconds between questions. In addition, he sharpens his pencil twice, which takes 20 seconds each time. The test begins promptly at 10:00 am. When Carl hands in his completed test, what time is it?

Answer 1

The time will be 10:42:40 am. = 10:42
`(2)/(3)` am.

Explanation:

∵ The time of 10 questions = 10 × 30 = 300 sec. ÷ 60 = 5 min.

∵ The time of 15 questions = 15 × 40 = 600 sec. ÷ 60 = 10 min.

∵ The time of 12 questions = 12 × 2 = 24 min.

∵ The total of the questions = 10 + 15 + 12 = 37

∵ The time of total rests between the questions = 36 × 5 = 180 ÷ 60 = 3 min.

* Note: (The rests time less than the number of questions by 1 because there is no rest after the last question)

∵ The time of sharpens = 2 × 20 = 40 sec. ÷ 60 =
`(2)/(3)` min.

∴The total time of the test = 5 + 10 + 24 + 3 +
`(2)/(3)` =
`42(2)/(3)` min.