Pyarelal does a job that takes him 8 hours everyday. He starts working

Question

Pyarelal does a job that takes him 8 hours everyday. He starts working at 10 am and finishes at 6 pm and earns $100 for those 8 hours of work. He however needs a cup of tea everyday and takes 15 minutes to drink it. But the cup of tea also increases his efficiency by 10%. At what time should he drink tea so that he finishes his work on time? Assume that he works for all the remaining time.

A. 4:30 PM
B. 4:15 PM
C. 3:30 PM
D. 3:15 PM
E. 3:10 PM

A. 4:30 PM
B. 4:15 PM
C. 3:30 PM 
D. 3:15 PM
E. 3:10 PM

Lipun · Accepted Answer

Let total work be 32 units.

8 hrs --> 32 units
=> 15 mins --> 1 unit

Let him work for x 15 mins intervals before tea break. So work done before break = x*1 = x

After break his efficiency increases by 10% => work done every 15 mins becomes 1.1 units
Number of 15 mins intervals remaining after break = 32-x-1 = 31-x
For each of the (31-x) 15 mins interval he does 1.1 units of work.

=> x + (31-x)*1.1 = 32
=> x + 34.1 - 1.1x = 32
=> 0.1x = 2.1
=> x = 21
Converting x into hours, 21/4 = 5 hrs and 15 mins

Ans: 3.15 pm

gurmukh · Answer

x×1 + (31/4-x)×1.1= 8
x - 1.1x = 8- 31×1.1÷4
-0.1x =-0.525
 X = 5.25
At 3:15
Option D is the answer

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yashikaaggarwal · Answer

Let pyarelal does 4 work every hour.
1 work in 15 min.
After drinking tea his efficiency increases by 10%
So he does 1.1 work in every 15 min after drinking tea.
Also he missed 1 work during those 15 min tea break.
Total work he has to do = 4*8 = 32
He has to complete his 1 work in the remaining time so that he can complete it on time.
He does 4/10 fraction of his missed 1 work every hour

Therefore, he did 4/10 fraction in between 5-6 PM 
Another 4/10 work in between 4-5 PM
Rest 2/10 is done in half an hour. 3:30-4 pm.
So he drink his tea 15 before 3:30 that is 3:15.

Answer is D

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Pln · Answer

How did u arrive at 4/10 fraction?

Posted from my mobile device

manikmehta95 · Answer

here, we only need to calculate time required to complete the work not done in 15 mins(spent drinking tea) according to the change of rate of work after drinking tea. 
let total work = 1 unit

if work done in 8 hrs = 1 unit
then, work done per hr = 1/8 unit per hr (also called rate of work)
after drinking tea, change in rate of work = (1/8)*0.1 unit per hr

time spent in hrs drinking tea = 1/4 hr
=> work missed while drinking tea = (1/4)*(1/8)
=> time required to complete the missed work = change in rate of work * time required(assume t') = (1/8)*0.1*t'
=> (1/8)*0.1*t' = (1/4*8)
=> t' = 2.5 hrs = time spent after drinking tea
=> total time = 2.5+0.25(to drink tea) = 2.75 hrs = 2hrs 45 min before 6:00PM

ANS: 3:15 PM

GiovanniMalfitano · Answer

(x/1,1)+ 1/4 = x time needed to recover the tea break

x = 11/4 = 2 h 45 m

6.00 - 2.45 = 3.15 answer D

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Pyarelal does a job that takes him 8 hours everyday. He starts working

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