Fatima's alarm clock gains 6 minutes every hour. She set it right at 7 a.m. When it shows 12:30 p.m., what is the correct time?

11:30 a.m.Correct answerYour answer11:54 a.m.Correct answerYour answer11:57 a.m.Correct answerYour answer12:00 noonCorrect answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer D

Correct answer: D

The clock shows 66 minutes for every 60 true minutes.
It has shown 5 h 30 min $= 330$ minutes since 7 a.m.
True time passed $= 330 \times \frac{60}{66} = 300$ minutes $= 5$ hours, so it is 12:00 noon.

Worth noting

11:57 a.m. multiplies 6 minutes by the 5.5 hours on the DIAL (33 minutes). The gain is 6 minutes per TRUE hour, and only 5 true hours have passed, so the clock is 30 minutes ahead.

Concept: Gain per true hour, not per dial hour
Typical timeTypical: 120 s
Your timeYours: —

The rule this testsClocks that gain or lose

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Ten questions from Calendars and Clocks, at your own pace.

Fatima's alarm clock gains 6 minutes every hour. She set it right at 7 a.m. When it shows 12:30 p.m., what is the correct time?

Explanation