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Q:

An air conditioner can cool the hall in 40 miutes while another takes 45 minutes to cool under similar conditions. If both air conditioners are switched on at same instance then how long will it take to cool the room approximately ?

A) 18 minutes B) 19 minutes
C) 22 minutes D) 24 minutes

Answer:   C) 22 minutes



Explanation:

Let the two conditioners be A and B

 

'A' cools at 40min

 

'B' at 45min

 

Together = (a x b)/(a + b)

= (45 x 40)/(45 + 40)

= 45 x 40/85

= 21.1764

= 22 min (approx).

Q:

Akash is 3 times as good a workman as Baldev and therefore is able to finish a job in 40 days less than Baldev. Working together, they can finish it in _____.

A) 15 days B) 60 days
C) 20 days D) 10 days
 
Answer & Explanation Answer: A) 15 days

Explanation:
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0 1
Q:

A can do a work in 12 days and B in 24 days. If they work on it together for 4 days, then what fraction of work is left?

A) 1/3 B) 1/2
C) 1/4 D) 1/5
 
Answer & Explanation Answer: B) 1/2

Explanation:
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Q:

P, Q and R together can make a table in 40 minutes. P and Q together can make it in 60 minutes. How much time (in minutes) will R alone take to make the table?

A) 100 B) 120
C) 90 D) 150
 
Answer & Explanation Answer: B) 120

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Q:

A can do a work in 15 days and B in 9 days. If they work on it together for 5 days, then what fraction of work is left?

A) 1/6 B) 3/7
C) 1/3 D) 1/9
 
Answer & Explanation Answer: D) 1/9

Explanation:
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Q:

X, Y and Z can do a piece of work in 30,40 and 50 days respectively. All three of them began the work together but Y left 4 days before completion of the work. In how many days was the work completed?

A) 660/47 B) 640/47
C) 680/47 D) 665/47
 
Answer & Explanation Answer: A) 660/47

Explanation:
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1 38
Q:

A and B together do a job in 12 days and A could do the job in 20 days if he worked alone. How many days would B take to do the job if he worked alone?

A) 30 B) 25
C) 24 D) 15
 
Answer & Explanation Answer: A) 30

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1 84
Q:

A, B and C can do a job working alone in 12, 16 and 24 days respectively. In how many days they can do the job if they worked together?

A) 16/3 B) 15/4
C) 17/3 D) 19/4
 
Answer & Explanation Answer: A) 16/3

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Q:

A, B and C can do a job working alone in 12, 16 and 24 days respectively. In how many days they can do the job if they worked together?

A) 16/3 B) 15/4
C) 17/3 D) 19/4
 
Answer & Explanation Answer: A) 16/3

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