A clock loses a minute every three hours for 4 days and gain

Question

A clock loses a minute every three hours for 4 days and gains 1% in the subsequent 6 days. If it was set right on Friday at 11 AM, what will be the time at the end of 10 days?

A. 11:54:40 AM
B. 11:56:24 AM
C. 12:16:40 PM
D. 11:54:24 AM
E. 12:06:36 PM

Bunuel · Accepted Answer

Clock loses: 1 minute in 3 hours = 8 minutes in 24 hours = 32 minutes in 4 days.
Clock gains: 1% in the subsequent 6 days = 1% in 6*24*60 minutes = 86.40 minute in 6 days;

Net gain in 10 days = 86.40 - 32 = 54.4 minutes.

11AM + 54.4 minutes = 11:54 and 4/10th of a minute or 24 seconds.

Answer: D.

jjack0310 · Answer

Its kinda confusing what exactly 1% is referring to. 
1% minute? 
1% hours?

Bunuel's explanation makes sense if you say the gain is 1% minutes but how do you know 1% not hours?
I guess, the question would be consistent and thus 1% has to refer to minutes, but still...

Bunuel · Answer

Given: a clock gains 1% in 6 days, so it gains 1% of 6 days --> clock gains: 1% in 6*24*60 minutes = 86.40 minute in 6 days;

Asifpirlo · Answer

Loses 8 minutes each day.
so total loss = 4×8 = 32min

subsequent 6 days = 6×24×60 minutes
1% gain = ( 6×24×60)/100 = 86.4 minutes

so, total gain = 86.4 - 32 = 54.4 min = 54 + 0.4 min = 54 minutes + 0.4 × 60 seconds = 54min + 24seconds

10 days later the clock should be 54 min and 24seconds fast.
so time , 11:54:24 am (Answer D)

jjack0310 · Answer

I understand the answer. I got the same result, but only after I looked at your solution as to what 1% was referring to. But thanks anyways.

saadis87 · Answer

Its not that hard once someone figures out what 1% refers to...which well it should be a little clearer

ShashankDave · Answer

After looking at your solution..it was easy to understand..but I tried something different..I can't figure out what's wrong with my solution..

In 4 days, the clock lost 32 minutes..converting it into percentage 
 \frac{32}{60*24*4} * 100

gives 0.55% ~ 0.5%

And then it gains 1% in the next 6 days..
so in total of ten days the time will become
(99.5 * 1.01) in %age terms..99.5 because it lost 0.5% in the first 4 days

= 100.49%
or 0.5% gain of the ten days' time 
or
24*10*0.005

but no answer justifies this!

What am I doing wrong?

Krotishka1 · Answer

Gotta agree that it is not clear at all what 1% means

JeffTargetTestPrep · Answer

Since there are 4 x 24 = 96 hours in four days, the clock loses 96/3 = 32 minutes in the first 4 days.

In the next 6 days, the clock gains 0.01 x (6 x 24) = 1.44 hours = 86.4 minutes = 86 minutes and 24 seconds

Subtracting 32 minutes from the gain we have that the clock gains:

54 minutes and 24 seconds

Thus, the clock will now read 11:54:24 AM.

Answer: D

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

A clock loses a minute every three hours for 4 days and gain

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

A clock loses a minute every three hours for 4 days and gain

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards