A wall clock moves 10 minutes fast in every 24 hours. The clock was set right to show the correct time at 8:00 a.m. on Monday. When the clock shows the time 6:00 p.m. on Wednesday, what is the correct time ?

Answer is (a).

In 24 hours, the correct clock moves 24 × 60 = 1440 minutes, whereas the incorrect clock will move 1440 + 10 = 1450 minutes. So we establish a basic relationship: for every 1440 minutes the correct clock moves, the incorrect clock moves 1450 minutes.

Now by the condition given in question the INCORRECT clock has moved 24 + 24 + 10 = 58 hours (i.e. 58×60 minutes).

If the INCORRECT clocks moves 1450 minutes, CORRECT clock moves 1440 minutes.

If the INCORRECT clock moves 1 minute, CORRECT clock moves 1440/1450 minutes.

But in our case INCORRECT clock has moved 58 hrs × 60 min /hr = 3480 minutes.

So, if the INCORRECT clock moved 3480 minutes, the correct clock will have moved (1440×3480)/1450 = 3456 minutes.

Converting 3456 min into hours we have 3456/60 = 573/5 or 57 hours 36 minutes. Ans.(a)