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Q:

A is thrice efficient as B and C is twice as efficient as B. what is the ratio of number of days taken by A,B and C, when they work individually?

A) 2:6:3 B) 2:3:6
C) 1:2:3 D) 3:1:2

Answer:   A) 2:6:3

Explanation:

                                                       A    :    B    :    C

Ratio of efficiency                    3     :    1    :    2

Ratio of No.of days               \inline \fn_jvn \left \{ \inline \fn_jvn \frac{1}{3}     :    \inline \fn_jvn \frac{1}{1}    :   \inline \fn_jvn \frac{1}{2}  \inline \fn_jvn \left \right \}

     or                                              2    :    6    :    3

Hence A is correct.     \inline \fn_jvn \left [ \because Time \prec \frac{1}{Eficiency} \right ]

Q:

Sixty men can stitch 150 shirts in 30 days working 8 hours a day. In how many days can 35 men stitch 200 shirts working 6 hours a day ?

A) 87.5 B) 89
C) 91.5 D) 93.5
 
Answer & Explanation Answer: C) 91.5

Explanation:

We have M1 D1 H1 / W1 = M2 D2 H2 / W2 (Variation rule)
(60 x 30 x 8)/ 150 = (35 x D2 x 6) / 200
D2 = (60 x 30 x 8 x 200) / (150 x 35 x 6) => D2 = 91.42 days =~ 91.5 days.

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Q:

A can complete a piece of work in 12 days and B is 60% more efficient than A. In how many days B will complete the same work  ?

A) 8.7 hrs B) 5.2 hrs
C) 5 hrs D) 7.5 hrs
 
Answer & Explanation Answer: D) 7.5 hrs

Explanation:

Ratio of times taken by A and B = 160 : 100
A can do the work in 12 days
Let B can do the work in "D" days
=> 160:100 = 12 : D
=> D = 12 x 100/160 = 7.5 hrs

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Q:

A can finish a work in 18 days and B can do the same work in half the time taken by A. then, working together, what part of the same work they can finish in a day ?

A) Total work B) One-fourth work
C) Half work D) Two-third work
 
Answer & Explanation Answer: C) Half work

Explanation:

A can do the work = 18 days
B can do the work = 18/2 = 9 days
(A + B)'s 1 day work = 1/18 + 1/9 = 1/6
=> In 3 days = 3x1/6 = 1/2 work is completed.

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Q:

10 boys can complete a work in 7 days and 10 girls take 14 days to complete the work. How many days will 5 boys and 10 girls take to complete the work ?

A) 13 days B) 10 days
C) 7 days D) 16 days
 
Answer & Explanation Answer: C) 7 days

Explanation:

1 boy's 1 day work = 1/70
1 girl's 1 day work = 1/140
(5 boys + 10 girls)'s 1 day work
= (5/70 + 10/140) = (1/14 + 1/14) = 1/7

5 boys and 10 girls will complete the work in 7 days.

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Q:

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

A) 9 days B) 11 days
C) 13 days D) 15 days
 
Answer & Explanation Answer: C) 13 days

Explanation:

Ratio of times taken by A and B = 100 : 130 = 10 : 13.
Suppose B takes x days to do the work.

Then, 10 : 13 :: 23 : x     =>     x = ( 23 x 13/10 )     =>     x = 299 /10.

A's 1 day's work = 1/23 ;
B's 1 day's work = 10/299 .

(A + B)'s 1 day's work = ( 1/23 + 10/299 ) = 23/299 = 113 .

Therefore, A and B together can complete the work in 13 days. 

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