Clock Problem !! tough one !

the slower clock loses 3 mins per hour and the faster one gains 5 mins per hour

so over all the faster clock is only 2 mins ahead of the slower clock

the faster clock gains 2 mins per hour over the slower clock so it gains 48 mins in the entire day

Now the only way for the clocks to strike 12 at midnight together is if the faster clock gains an entire day over the slower one

There are 60*24= 1440 mins in a day

every day the clock gains 48 mins

there fore the clock needs 1440/48 = 30 days to gain a day

Hence the time required is more than 3 weeks to strike 12 at midnight again

ANSWER E

I think that the fastre clock gains 8 mins (and not 2) over the slower one.
So number of days required to gain 24 hours would be 1440/(24*8) ~ 7.5 days ~ more than 1 week.

hey thanks gautamberry!!

indeed was a good approach ! and the answer Is E

Vishu

ur welcome...........and thank you for the problem.........was a damn good one..........

gautamberry wrote:the slower clock loses 3 mins per hour and the faster one gains 5 mins per hour

so over all the faster clock is only 2 mins ahead of the slower clock

the faster clock gains 2 mins per hour over the slower clock so it gains 48 mins in the entire day

Now the only way for the clocks to strike 12 at midnight together is if the faster clock gains an entire day over the slower one

There are 60*24= 1440 mins in a day

every day the clock gains 48 mins

there fore the clock needs 1440/48 = 30 days to gain a day

Hence the time required is more than 3 weeks to strike 12 at midnight again

ANSWER E

can u explain how u got faster ahead only by 2 min...sh'dnt it be 8 min?

gautamberry wrote:the slower clock loses 3 mins per hour and the faster one gains 5 mins per hour

so over all the faster clock is only 2 mins ahead of the slower clock

How come it is 2???

the faster clock gains 2 mins per hour over the slower clock so it gains 48 mins in the entire day

Now the only way for the clocks to strike 12 at midnight together is if the faster clock gains an entire day over the slower one

There are 60*24= 1440 mins in a day

every day the clock gains 48 mins

there fore the clock needs 1440/48 = 30 days to gain a day

Hence the time required is more than 3 weeks to strike 12 at midnight again

ANSWER E

vishubn wrote:hey thanks gautamberry!!

indeed was a good approach ! and the answer Is E

Vishu

What is the source of this Qn?

I had few old materials from GMAT800

vishu

few of the questions are quite head breaking

Hi, the answer is wrong see here

First
Day 12.00 12.00

1 57.00 65.00
2 57.00 65.00
3 57.00 65.00
4 57.00 65.00
5 57.00 65.00
6 57.00 65.00
7 57.00 65.00
8 57.00 65.00
9 57.00 65.00
10 57.00 65.00
11 57.00 65.00
12 57.00 65.00
13 57.00 65.00
14 57.00 65.00
15 57.00 65.00
16 57.00 65.00
17 57.00 65.00
18 57.00 65.00
19 57.00 65.00
20 57.00 65.00
21 57.00 65.00
22 57.00 65.00
23 57.00 65.00
24 57.00 65.00

oneday 1368 1560
so the slower clock will be showing 22.48 and faster clock will be slowing 26.00 (which means 02.00)

that mean faster clock get 192 means faster daily compared to slower one.

in order for the two clocks to reach 12 again they need to travel 24*60=1440 minutes
1440/192=7.5 days abt a week if i am wrong please explain me.

one more after 7.5 days of actual clock it will be mid afternoon so need another 7.5 days to reach midnight a total of 15 day.
so 2 weeks must be completed.

what do you say?

gautam.,
can u explain this...
Suppose time is 1.00 am
After one hr exact time 2.00 am
Slower watch will show - 1.57 am
Faster watch will show - 2.05 am
So,diif is 8 mins..how it is 2 mins pls explain by some example.