6
Q:

In a public bathroom there are n taps 1,2,3...n. Tap1 and Tap2 take equal time to fill the tank while Tap3 takes half the time taken by Tap2 and Tap4 takes half the time taken by Tap3. Similarly each next number of tap takes half the time taken by previous number of Tap i.e, K-th  Tap takes half the time taken by (K-1)th Tap.

If the 10th tap takes 2 hours to fill the tank alone then what is the ratio of  efficiency of 8th tap and 12th tap, respectively?

A) 4:1 B) 5:3
C) 16:1 D) 1:16

Answer:   D) 1:16



Explanation:

Time taken by 8th tap = \inline 2\times 2\times 2 = 8 hours

and time taken by 12th tap = \inline 2\times \frac{1}{2}\times \frac{1}{2} = \inline \frac{1}{2} hour

Ratio of time taken by 8th 8th tap and 12th tap = \inline 8:\frac{1}{2} =16:1

Therefore, Ratio of efficiencies of 8th tap and 12th tap =1:16

Q:

P is 30% more efficient than Q. How much time will they, working together, take to complete a job which P alone could have done in 23 days?

A) 16 days B) 13 days
C) 15 days D) 12 days
 
Answer & Explanation Answer: B) 13 days

Explanation:

Ratio of times taken by P & Q = 100 : 130 = 10:13

Let Q takes x days to do the work

Then, 10:13 :: 23:x

=> x = 23x13/10

=> x = 299/10

P's 1 day's work = 1/23

Q's 1 day's work = 10/299

(P+Q)'s 1 day's work = (1/23 + 10/299) = 23/299 = 1/13

Hence, P & Q together can complete the work in 13 days.

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10 222
Q:

If 2 men and 3 women can do a piece of work in 8 days and 3 men and 2 women in 7 days. In how many days can the work be done by 5 men and 4 women working together?

A) 3 days B) 6 days
C) 4 days D) 2 days
 
Answer & Explanation Answer: C) 4 days

Explanation:

From the given data,

=> (2 M + 3W) 8 = (3M + 2W)7

=> 16M + 24W = 21M + 14 W

=> 10W = 5M

=> 2W = M

=> 14W × ? = 7W × 8

? = 4 days

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11 291
Q:

28 Men and 52 women working together completes a work in 22.5 days. 35 men and 65 women working together on same work will complete it in how many days?

A) 16 B) 18
C) 19 D) 21
 
Answer & Explanation Answer: B) 18

Explanation:

clearly total persons are increased in => 28/35 :: 52/65 = 4:5

As time is inversely proportional to men, so total time will decrease in the ratio 5:4

Hence, 22.5 x 4/5 = 18 days.

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6 156
Q:

A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left?

A) 8/15 B) 7/9
C) 6/13 D) 4/11
 
Answer & Explanation Answer: A) 8/15

Explanation:
P's 1 day's work = 1  
15
Q's 1 day's work = 1  
20
(P + Q)'s 1 day's work = ( 1 + 1 ) = 7  
15 20 60
(P + Q)'s 4 day's work = ( 7 x 4 ) = 7  
60 15
Therefore, Remaining work = ( 1 - 7 ) = 8 .
15 15
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7 210
Q:

X can complete the work in 10 days, Y can do the same in 15 days. If they are hired for 5 days to do the work together, what is the work that left unfinished?

A) 1/3 B) 2/3
C) 1/6 D) 5/6
 
Answer & Explanation Answer: C) 1/6

Explanation:

Given X can do in 10 days

=> 1 day work of X = 1/10

Y can do in 15 days

=> 1 day work of Y = 1/15

1day work of (X + Y) = 1/10 + 1/15 = 1/6

Given they are hired for 5 days

=> 5 days work of (X + Y) = 5 x 1/6 = 5/6

Therefore, Unfinished work = 1 - 5/6 = 1/6 

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8 354