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Modulo Arithmetic & Congruence · Question 8 of 97

At what time of day is the second service?

Question 8

EasyOriginal question

A factory runs round the clock. A machine is serviced every 30 hours, the first service at 06:00 on a Monday. The shifts run from 06:00 to 14:00, 14:00 to 22:00 and 22:00 to 06:00.

At what time of day is the second service?

06:00Correct answerYour answer18:00Correct answerYour answer00:00Correct answerYour answer12:00Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer D

Correct answer: D

The time of day works modulo 24: $6 + 30 = 36$ , and $36 = 24 + 12$ .
So the second service is at 12:00, on Tuesday.

Worth noting

06:00 adds 24 hours instead of 30.

Concept: The 24-hour clock
Typical timeTypical: 90 s
Your timeYours: —

The rule this testsThe modulo operation

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