11
Q:

Two pipes A and B can fill a tank in 24 hours and  hours respectively. Harihar opened the pipes A and B to fill an empty tank and some times later he closed the taps A and B , when the tank was supposed to be full. After that it was found that the tank was emptied in 2.5 hours because an outlet pipe "C" connected to the tank was open from the beginning. If Harihar closed the pipe C instead of closing pipes A and B the remaining tank would have been filled in :

A) 2 hours B) 8 hours
C) 6 hours D) 4 hours

Answer:   B) 8 hours

Explanation:

Efficiency of Inlet pipe A = 4.16%                              

Efficiency of Inlet pipe B = 5.83%                              

 Efficiency of A and B together = 100 %  

Now, if the efficiency of outlet pipe be x% then in 10 hours the capacity of tank which will be filled = 10 *  (10 - x)

Now, since this amount of water is being emptied by C at x% per hour, then            

           x = 8%

Therefore, in 10 hours 20% tank is filled only. Hence, the remaining 80% of the  capacity will be filled by pipes A and B  in 80/10 = 8 hours 

Q:

A group of men can complete a job in K hours. After every 4 hours, half the number of men working at that point of time leave the job. Continuing this way if the job is finished in 16 hours, what is the value of K ?

A) 7 hrs B) 7.5 hrs
C) 8 hrs D) 8.25 hrs
 
Answer & Explanation Answer: B) 7.5 hrs

Explanation:

Let there are L men

job requires LK man hours.

job completed in first 4 hrs = Lx4 = 4L
job completed in next 4 hrs = 4xL/2 = 2L
job completed in next 4 hrs = 4xL/4 = L
job completed in last 4 hrs = 4xL/8 = L/2
4L + 2L + L + L/2 = KL
K = 7+1/2 = 7.5 hours.

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1 7
Q:

A can do a work in 9 days, B can do a work in 7 days, C can do a work in 5 days. A works on the first day, B works on the second day and C on the third day respectively that is they work on alternate days. When will they finish the work ?

A) [7 + (215/345)] days B) [6 + (11/215)] days
C) [6 + (261/315)] days D) [5 + (112/351)] days
 
Answer & Explanation Answer: C) [6 + (261/315)] days

Explanation:

After day 1, A finishes 1/9 of the work.

After day 2, B finishes 1/7 more of the total work. (1/9) + (1/7) is finished.

After day 3, C finishes 1/5 more of total work. Total finished is 143/315.

So, after day 6, total work finished is 286/315.

Now remaining work = 315 - 286 = 29 /315

On day 7, A will work again

Work will be completed on day 7 when A is working. He must finish 29/315 of total remaining work.

Since he takes 9 days to finish the total task, he will need 261/315 of the day.

Total days required is 6 + (261/315) days.

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3 25
Q:

One girl can eat 112 chocolates in half a minute, and her boy friend can eat half as many in twice the length of time. How many chocolates can both boy and girl eat in 12 seconds ?

A) 44 B) 32
C) 56 D) 49
 
Answer & Explanation Answer: C) 56

Explanation:

Girl eats 112 chocolates in 30 sec
so she can eat in 12 sec is 12 x 112/30 = 44.8 chocolates.

Her boy friend can eat one-half of 112 in twice of 30 sec
so he can eat 56 in 60 sec
Then he can eat in 12 sec is 56 x 12/60 = 11.2 chocolates.

Hence, together they can eat
=> 44.8 + 11.2
56 chocolates in 12 seconds.

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5 12
Q:

Two boys and a girl can do a work in 5 days, while a boy and 2 girls can do it in 6 days. If the boy is paid at the rate of 28$ a week, what should be the wages of the girl a week ?

A) 24 $ B) 22 $
C) 16 $ D) 14 $
 
Answer & Explanation Answer: C) 16 $

Explanation:

Let the 1 day work of a boy=b and a girl=g, then
2b + g = 1/5 ---(i) and
b + 2g = 1/6 ---(ii)
On solving (i) & (ii), b=7/90, g=2/45
As payment of work will be in proportion to capacity of work and a boy is paid $ 28/week,
so a girl will be paid 28x  = 16 $.

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3 12
Q:

A constructor estimates that 4 people can paint Mr. Karthik's house in 6 days. If he uses 5 people instead of 4, how long will they take to complete the job ?

A) 3 days B) 26/3 days
C) 13/4 days D) 24/5 days
 
Answer & Explanation Answer: D) 24/5 days

Explanation:

we know that m1 x d1 = m2 x d2
=> 4 x 6 = 5 x d
where d = no. of days taken by 5 men to paint
d = 24/5 days.

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