# clock problem

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• Jul 14th 2013, 07:47 PM
hisajesh
clock problem
A watch, which gains 5 seconds every 3 minutes, is set right at 6a.m. What is the true time in the afternoon of the same day when the watch indicates a quarter past 3?

My answer is 2:59:15 seconds but the book answer is 3:00:00
Kindly check if you get a chance, appreciate your help.
• Jul 15th 2013, 08:01 AM
HallsofIvy
Re: clock problem
Your book's answer is correct. Since you did not show how you got your answer it is impossible to say what you might have done wrong.
• Jul 15th 2013, 10:38 AM
bjhopper
Re: clock problem
Time elapsed 15:15:00 on clock minus start time of 6:00:00 = 9:15:00 or 9.25 hrs which equals 555minutes
Clock runs fast 555/3 *5 = 925 seconds fast 15 min 25 sec
Correct time 14:59:35
What did I do wrong?
• Jul 15th 2013, 02:12 PM
hisajesh
Re: clock problem
@HallsOf Ivy I did similiar to bjhopper

the difference between 6 a.m to 3:15 pm is 9 hours and 15 minutes which is equal to 555 minutes.
So we have 555/3 = 185 minutes, which is equal to 185 * 5= 925 seconds or 15 minutes and 25 seconds. So I get 2:59:35.
• Jul 15th 2013, 02:28 PM
topsquark
Re: clock problem
I'll defer a direct answer until HallsofIvy gets back, but have you considered that the extra rate of the fast clock is not necessarily going to have a chance to act on the full 5 seconds in those last three minutes?

-Dan