Pats watch gains an extra 10 seconds every 2 hours. Kims watch loses

Question

Pat’s watch gains an extra 10 seconds every 2 hours. Kim’s watch loses 5 seconds every 3 hours. If both watches are set to the correct time at 8 o’clock in the morning and run without interruption, after 72 hours, what will be the difference in time between Pat’s watch and Kim’s watch?

(A) 4 min

(B) 6 min

(C) 6 min 40 sec

(D) 7 min 30 sec

(E) 8 min

PS03258

Bunuel · Accepted Answer

Pat's watch gains an extra 10 seconds every 2 hours. Kim's watch loses 5 seconds every 3 hours. If both watches are set to correct time at 8 o'clock in the morning and run without interruption, after 72 hours, what will be the difference in time between Pat's watch and Kim's watch?

(A) 4 min

(B) 6 min

(C) 6 min 40 sec

(D) 7 min 30 sec

(E) 8 min

(A) 4 min

(B) 6 min

(C) 6 min 40 sec

(D) 7 min 30 sec

(E) 8 min

In 72 hours Pat's watch will  gain  an extra 72/2*10 = 360 seconds.

In 72 hours Kim's watch will  lose  72/3*5 = 120 seconds.

Hence the difference will be 360 + 120 = 480 seconds or 8 minutes.

Answer: E.

Hope it helps.

Abhii46 · Answer

In 72 hours Pat's watch will gain 360 seconds, since in 2 hours it gains 10 seconds, that means in 1 hour 5 seconds and in 72 hours 72*5 seconds, i.e. 360 seconds or 6 mins.

Kim's watch loses 5 seconds in 3 hours, in 72 hours it will loose 72/3 * 5 = 24*5 = 120 seconds = 2 mins.

Total difference 6 - (-2, it lost 2 mins ) = 6 + 2 = 8 mins.

Zarrolou · Answer

First we have to bring everything to the same scale, to make life easier:

10 sec ->2h = 5 sec -> 1h 
 5 sec->3h = \frac{5}{3}sec->1h

Pat's watch will gain a total of  5 sec * 72 h = 360 sec 
Kim's watch will lose a total of 5/3 sec * 72 h = 120 sec

<----------------|-------------------->
(-120sec)----- 0------------( +360 sec)

tot distance =  120+360=480 sec = 8 min

E

tulsa · Answer

This is how I solved this..

10s/2h, 72/2 -> 36 (and then the /h value x10) -> 36x10 = 360. Go on with /6 -> 6min
5s/3h, 72/3 -> 24 (and then the /h value x5) -> 36x5 = 120. Go on with /6 -> 2 (sine it's a loss it's -2)

-2 to 6 = 8, hence E (I did not get it right first since I personally missed the "loss")

gracie · Answer

watch P gains 5 sph
watch K loses 5/3 sph
5+5/3=20/3 sph
72 h*20/3 sph=480 s 
480 s/60 spm=8 min

duahsolo · Answer

In every 6 hours, Pat GAINS (10 + 10 +10) = 30 seconds

In every 6 hours, Kim LOSES (5 + 5) = 10 seconds or "GAINS" (-10) seconds

In every 6 hours, the time difference ==> 30 - (-10) = 40 seconds

In 72 hours, time difference ==> 72hrs/6hrs * 40 seconds = 480 seconds or 8 minutes

(E)

AkshdeepS · Answer

(A) 4 min

(B) 6 min

(C) 6 min 40 sec

(D) 7 min 30 sec

(E) 8 min

Pat's watch = 2 hrs ---- 10 seconds addition

72 hours ---- 360 seconds gain

Kim's watch ---- 3 hrs --- 5 seconds loss

72 hours ---- 120 seconds loss

Difference = 360 - ( - 120)

= 480/60

8 minutes

akadiyan · Answer

Pat's watch gains an extra 10 seconds every 2 hours. Kim's watch loses 5 seconds every 3 hours. If both watches are set to correct time at 8 o'clock in the morning and run without interruption, after 72 hours, what will be the difference in time between Pat's watch and Kim's watch?

(A) 4 min

(B) 6 min

(C) 6 min 40 sec

(D) 7 min 30 sec

(E) 8 min

Pat:
After 72 hours i.e after 36 intervals, PAT's watch would have gained 6 minutes

Kim:
Loses 5 seconds every 3 hours. In 72 hours i.e loses 5 seconds 24 times , that is equal to 2 minutes.

Pat's clock gains 6 minutes and kim's watch loses 2 minutes.

So time difference between watches is 8 Minutes

Ans:   E

ScottTargetTestPrep · Answer

Pat’s watch gains 10 x 72/2 = 10 x 36 = 360 seconds in 72 hours.

Kim’s watch loses 5 x 72/3 = 5 x 24 = 120 seconds in 72 hours. We have to consider this as -120 since it’s the number of seconds lost.

Thus, the difference is 360 - (-120) = 480 seconds = 8 minutes.

Answer: E

DanTheGMATMan · Answer

Lovely little net rate problem:

https://www.youtube.com/watch?v=-RmX4cGwxXI

Sa800 · Answer

i dont know if i am overthinking this but

the clock started at 8 am and will run for 72 hours...so it will also END at 8 am but 3 days later (because 3 days = 72 hours)

and since Pats clock gains 10 seconds every two hours, he will approach that end time earlier (In other words after the first 2 hours, Pat will be ten seconds ahead so he has to run his clock for 10 seconds extra! -- to ensure than he actually meets the 72 hour run time for his clock--)

and since Kim is losing 5 seconds every 3 hours she will have to run her clock for a shorter amount of time (otherwise her true time of running the clock will go OVER the 72 hour mark)

so when do we truly know that their clocks truly ran for 72 hours exactly....? one person is gaining time and one person is losing time....

Bunuel · Answer

Yes, you are overthinking this. When the question says “after 72 hours,” it means 72  actual  hours, not 72 hours as shown on either faulty watch.

Pats watch gains an extra 10 seconds every 2 hours. Kims watch loses

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Pats watch gains an extra 10 seconds every 2 hours. Kims watch loses

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