Chain Rules - Online Quiz



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Following quiz provides Multiple Choice Questions (MCQs) related to Chain Rules. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz.

Questions and Answers

Q 1 - If 4/5th of a cistern is filled in 1 minute, how much more time will be required to fill the rest of it?

A - 20 seconds

B - 15 seconds

C - 12 seconds

D - 10 seconds

Answer : B

Explanation

Let the required time be x seconds.
Part filled = 4/5, Remaining part = (1- 4/5 ) = 1/5.
Less  part to be filled , less is the time taken     (direct)
4/5 :1/5 :: 60 : x ⇒ 4/5 * x = (1/5 * 60 ) = 12 ⇒ x= (12 * 5/4 ) = 15.
Required time = 15 seconds.

Q 2 - 3 men or 5 women can finish a piece of work in 12 days. How long will 6 men and 5 women take to finish the work?

A - 4 days

B - 10 days

C - 15 days

D - 20 days

Answer : A

Explanation

3 men = 5 women ⇒ 6 men =10 women
⇒ (6 men +5 women )= 15 women.
Let the required number  of days be x.
More women , less days      (Indirect)
15 : 5 :: 12 :  x ⇒ 15x = (5* 12 ) ⇒ x= (5*12)/15 = 4 days

Q 3 - 8 men can complete a piece of work in 12 days ; 4 women can complete it in 48 days and 10 children can complete the same piece of work in 24 days . In how many days can 10 men , 4 women and 10 children complete the same piece of work?

A - 5 days

B - 15 days

C - 28 days

D - 6 days

Answer : D

Explanation

1 man can complete the work in ( 12 * 8) = 96 days.
1 women can complete the work in ( 48 * 4) = 192 days.
1 child can complete the work in ( 24 * 10) = 240 days.
1 men 1 days work = 1/96, 1 women1 days work = 1/192.
1 child 1 days work = 1/240.
( 10 men + 4 women + 10 children) 1 days work = ( 10/ 96 + 4/192 + 10/240)
= (5/48 + 1 /48 + 1/24) = 8/48 = 1/6.
∴ They will do the work in 6 days.

Q 4 - A man and a boy working together can complete a work in 24 days . If for the last 6 days man alone the work , then it is completed in 26 days. How long will the boy take to complete the work alone?

A - 72 days

B - 20 days

C - 24 days

D - 36 days

Answer : A

Explanation

Let 1 men 1 days work be 1/x and 1 boy 1 days work be 1/y Then,
1/x + 1/y = 1/24
20/x + 20 / y +  6 /x )1 ⇒ 20 (1/x + 1/y) + 6/x = 1 ⇒ (20 * 24) + 6/x = 1 
⇒ 6/x = (1- 20/24) = 4 / 24 = 1/6 ⇒ 1/x = 1/ 36 ⇒ 1/y = ( 1/24 - 1/ 36 ) = 1/72.
∴ The boy along will do it in 72 days.

Q 5 - Two persons can complete a piece of work in 9 days. How many more persons are needed to complete double the work in 12 days?

A - 1

B - 2

C - 3

D - 4

Answer : A

Explanation

Let the required number of persons be x .
More work, more  persons          (direct)
More  days  , less persons          (Indirect)
Work      1:2
:: 2 : (2+x)
Days    12:9 
 1*12 * ( 2 + x ) = (2 * 9 *2 ) ⇒ ( 2 + x ) = 36/12 = 3 ⇒ x=1.

Q 6 - Four examiners can examine a certain number of answer papers in 10 days by working for 5 hours a day. For how many hours in a day would 2 examiners have to work in order to examine twice the number of answer papers in 20 days?

A - 15/2 hours

B - 8 hours

C - 7/2 hours

D - 10 hours

Answer : D

Explanation

Let the number of hours per days be x.
More days, less hours per days          ( Indirect)
Less examiners , more hours per days         ( Indirect)
More Ans. Books , more hours per days     ( direct)
Days         20 : 10 
     Examiners      2 : 4 :: 5 : x
Ans. Books   1 : 2 
∴ (20 * 2 * 1 * x) = ( 10 * 4 * 2* 5 ) ⇒ x = 400 / 40 = 10 hrs per days.

Q 7 - 8 men working for 9 hours a day complete a piece of work in 20 days . In how many days can 7 men working for 10 hours a day complete the same piece of work?

A - 41/2 days

B - 103/5 days

C - 21 days

D - 144/7 days

Answer : D

Explanation

Let the required number of days be x .
Less men , more days      ( Indirect)
More  working hours, less days      (Indirect)
Men    7: 8
:: 20 : x
Working hrs   10 : 9
∴ ( 7 * 10 * x ) = ( 8 * 9 * 20) ⇒ x = 8 * 9 * 20 / 7 * 10  = 144/7 = 144/7.

Q 8 - If the rent for grazing 40 cows for 20 days in Rs 740, how many cows can graze for 30 days on Rs 222?

A - 6

B - 8

C - 5

D - 12

Answer : B

Explanation

Let the required  number of   cows be x.
Less rent, less cows     (Direct)
More days, less cows    (Indirect)
Rent  740 : 222
:: 40 : x
Days  30: 20 
∴ ( 740 * 30 * x) = ( 222 * 20 * 40 ) ⇒ x = 222* 20 * 40 / 740 * 30 = 8 cows.

Q 9 - 2 men and 7 boys can do a piece of work in 14 days ; 3 men and 8 boys can do the same in 11 days . 8 men and 6 boys can do 3 times the amount of this work in

A - 21 days

B - 18 days

C - 24 days

D - 36 days

Answer : A

Explanation

Let 1 men 1 days work be 1/x and 1 boy 1 day work be 1/y
Then 2/x + 7/y = 1/14 ⇒ 2u + 7v = 1/14 -(i) When u= 1/x, v=1/y.
3/x +8/y =1/11 ⇒ 3u + 8v = 1/11?.(ii)
Multiplying (i) by (ii) by 2 and subtracting , we get:
5v = ( 3/14 ? 2/11) = 5/ 154 ⇒ v = 1/154
Putting v = 1/154 in (i) we get : 2u +7* 1/154 = 1/14
∴ 2u = (1/14- 1/22)= (11-7/54) = 4/154 = 2/77 ⇒ u=1/77.
(8 men +6 boys) 1 days work = (8/77 +6/154 ) = 22/154 = 1/7.
∴ 8men and 6 boys can do it in 7 days.
They will do thrice of this work in (3*7) days = 21days.

Q 10 - 20 men complete one third of a piece of work in 20 days. How many more men should be employed to finish the rest of the work in 25 more days?

A - 10

B - 12

C - 15

D - 20

Answer : B

Explanation

Work done = 1/3, Remaining work = (1- 1/3 ) = 2/3
Let the number of additional men be x.
More work, more men      (Direct)
More days , less men         (Indirect)
Work 1/3 : 2 /3
:: 20 : (20 +x)
Days 25:20
   1/3 * 25 * ( 20 + x) = 2 /3 * 20 *20 ⇒ (20 +x) = 32 ⇒ x=12.
Required number of days  = 12.


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