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 - A worker makes a toy every 2/3 hour. If he works for 15/2 hours, then how many toys will he makes?

A - 45/4

B - 47/4

C - 53/4

D - 55/4

Answer : A

Explanation

Let the required number of toys be x.
More time , more toys made   (Direct)
2/3 : 15/2 :: 1:x ⇒ 2/3 * x = 15/2 *1 ⇒ x= (15/2 *3/2 ) = 45 /4 = 45/4.
Required number  of toys = 45/4.

Q 2 - 10 men can finish the construction of a wall in 8 days. How many men are added to finish the work in half a day?

A - 160

B - 100

C - 120

D - 150

Answer : D

Explanation

Let the total number of men be x.
Less days , more men required    (Indirect)
1/2 : 8 :: 10 : x ⇒ 1/2 x =(8* 10 )⇒ x= (8* 10* 2*) = 160.
Number of men to be added = (160- 10 )=150.

Q 3 - 10 women can complete a piece of work in 8 days and 10 children take 12 days to complete it. How many days will 6 women and 3 children together take to complete the work?

A - 9 days

B - 12 days

C - 10 days

D - 8 days

Answer : C

Explanation

1 women can complete the work in ( 10 * 8) = 80 days.
1 child can complete the work in ( 10 * 12) = 120 days.
1 women 1 days work = 1/80, 1 child 1 days work = 1/120.
( 6women  + 3 children) 1 days work = ( 6 * 1/80 + 3 * 1/120) = ( 3 /40 + 1/40 ) = 4/40=1/10.
Required time 10 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 - If 9 men working hours 15/2 hours a day can finish a work in 20 days , then how many days will be taken by 12 men , working 6 hours a day to finish the work . It is given that 2 men of latter type work as much as 3 men of former type?

A - 19/2 days

B - 11 days

C - 25/2 days

D - 13 days

Answer : C

Explanation

2 men of latter type = 3 men of former tyes.
12 men of latter type = (3/2 *12) = 18 men of former tyes.
Let the required number of days be x.
More men , less days        (Indirect)
Men      18 : 9
:: 20 : x 
Working hrs  6 : 15 /2 
∴  18 *6 *x = 9 * 15/2 * 20 ⇒ x= 9 * 150/18 * 6 = 25/2 = 25/2 days.

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 - If 6 persons working 8 hours a day earn Rs 16800 per week , then 9 persons working 6 hours a day will earn per week?

A - Rs 17800

B - Rs 18900

C - Rs 19200

D - Rs 26800

Answer : B

Explanation

Let the required earning  be Rs x.
More persons , more earning      ( Direct)
Less hrs per day, less earning      ( Direct)
Persons   6:9
:: 16800 : x
Hrs / day      8 : 6
(6 * 8 *x ) = ( 9 * 6 * 16800) = X =9 * 6 * 16800/ 6 *8  = 18900.

Q 8 - If 18 binders bind 9000 books in 10 days , how many binders will be required to bind 6600 books in 12 days?

A - 55

B - 14

C - 13

D - 11

Answer : D

Explanation

Let the required number of binders be x.
Less books, less binders   (direct)
More days, less binders    (Indirect)
Books 9000:6600
Days   12:10                   :: 18 : x
∴ (9000* 12*x) = (6600 * 10 *18)⇒ x= 6600 * 10 *18/9000 *12 = 11

Q 9 - If a certain number of workmen can be a piece of work in 25 days , in what time will another set of an equal number of men do a piece of work twice as great , supposing that 2 of the first set can do as much work in an hour as 3 of the second set can do in an hour

A - 60 days

B - 75 days

C - 90 days

D - 105 days

Answer : B

Explanation

Let the required time be x days  .
Ratio of their speed = 1/2 : 1/3.
More work , more time    (Direct)
Less speed, more work    (Indirect)
Work 1:2                      :: 25:x
Speed 1/3 : 1/2 
∴ (1* 1/3 *x) = 2 *1/2 *25 ⇒ x=75days.

Q 10 - If x men working x hours per day can do x unit of work in x days , then y men working y hours per day would be able to do how much work in y days?

A - x2/y2 units

B - x3 / y2 unit

C - y2 / x3 unit

D - y3 / x2

Answer : D

Explanation

More men , more work (Direct)
More working hrs , more work (Direct)
More days , more work (Direct)
Let the required work be z units. Then,
Men          x:y
working hrs       x:y                       :: x:z
days                x:y
∴ x*x*x*z = y * y* y* x ⇒ z= y3 / x2 units.


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