Chain Rules - Online Quiz



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 21 cows eat as much as 15 buffaloes, how many cows will eat as much as 35 buffaloes?

A - 49

B - 56

C - 45

D - 47

Answer : A

Explanation

15 buffaloes = 21 cows ⇒ 1 buffalo = 21/15 cows = 7/5 cows
⇒35 buffaloes = (35 * 7/5 ) cows = 49 cows.

Q 2 - The Qutab minar casts a shadow 150m long at the same time when the vikes minar casts a shadow 120m long on the ground . If the height of the Vikes minar is 80m, what is the height of the Qutab Minar?

A - 100m

B - 120m

C - 150m

D - 180m

Answer : A

Explanation

Let the height of  the Qutab Minar be x metres.
Longer is the shadow , longer is the object    (Direct)
120 : 150 :: 80 : x ⇒ 120 * x = (150 *80)⇒ x= (150 *80)/120=100m.
Height of Qutab Miinar = 100m.

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 a job takes 12 workers 4 hours to complete, how long should it take 15 workers to complete the job?

A - 2 hrs 40 min

B - 3 hrs

C - 3 hrs 12 min

D - 3 hrs 24 min

Answer : C

Explanation

Let the required number of  hours b x.
More working , less  hours             (Indirect)
15 : 12 :: 4 : x = > 15 x = ( 12 * 4 ) ⇒ x= (12 * 4 ) /15 = 16 / 5 hrs = 3hrs 12 min.

Q 6 - A contract is to be completed in 46 days and 117 men were set to works , each working 8 hours a day. After 33 days , 7/4 of the work is completed . How many additional men may be employed so that the work may be completed in time , each man now working 9 hours a days?

A - 80

B - 81

C - 82

D - 83

Answer : B

Explanation

Let the required number of men be x.
Work done = 4/7 , Remaining work  = ( 1- 4/7 ) = 3/7.
Less days , more  men           (Indirect)
More hrs/day, less men         (Indirect)
Less work , less men         ( Direct)
Days   13 : 33
Hrs/days    9:8 :: 117 : ( 117 +x)
Work:  4/7  :  3/7
∴ 13 * 9 * 4/7 * ( 117 + x) = 33 * 8 * 3/7* 117
⇒ ( 117 + x ) = 33 * 8 * 3 * 117/13 * 9 * 4 = 198 ⇒ x = ( 198 ? 117) = 81.

Q 7 - Running at the same constant rate , 6 identical machines can produce 2700 bottle per minute . At this rate , how many bottles could 10 such machines produce in 4 minutes?

A - 648

B - 1800

C - 2700

D - 10800

Answer : B

Explanation

Let the required number  of bottles be x .
More machines, more bottles    ( Direct)
More time, more bottles      ( Direct)
Machines         6 : 10
:: 2700 : x
Time     1:4
(6 * 1 * x) = 10 * 4 * 2700 ) ⇒ 10 * 4 * 2700 / 6 = 1800 bottles.

Q 8 - In a hospital, there is a consumption of 1350 litres of milk for 70 patients for 30 days. How many patients will consume 1710 litres of milk in 28 days?

A - 59

B - 85

C - 95

D - 105

Answer : C

Explanation

Let the required number of patients be x .
More milk, more patients        (Direct)
Less days , more patients        (Indirect)
Litres   1350:1710
::70 : x 
Days       28 : 30
∴ ( 1350 * 28 * x ) = ( 1710 * 30 * 70) ⇒ x= 1710 * 30 * 70/ ( 1350 * 28 ) = 95 patients.

Q 9 - A contractor employed 30 men to do a piece of work in 38 days. After 25 days he employed 5 men more and the work was finished one day earlier. How many days , he would have been behind , if he had not employed additional men?

A - 1 day

B - 5/4 days

C - 3 days

D - 7/4 days

Answer : A

Explanation

After 25 days , 35 men finish the remaining work in (38 - 25 - 1) = 12 days.
35 men can finish the remaining work in 12 days.
30 men can finish it in (12 * 35) /30  days = 14 days , i.e. 1 day behind.

Q 10 - A garrison had provision for a certain number of days . After 10 days , 1/5 th of the men desert and it is found that the provision will now last just as long as before. How long was that?

A - 35 days

B - 15 days

C - 25 days

D - 50 days

Answer : D

Explanation

Initially, let x men had provisions for y days. Then, x men had provisions for (y-10)  days.
(x- x/5) men had provisions for y days.
∴ x ( y-10) = 4x /5 *y ⇒5xy - 50 x = 4xy
⇒ xy - 50x = 0 ⇒ x (y-50) = 0 ⇒ y = 50.
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