# Aptitude Questions : Chain Rule Set 3

Hello Aspirants. Welcome to Online Maths in AffairsCloud.com. Here we are creating question sample in Chain Rule, which are common for competitive exams. We have included Some questions that are repeatedly asked in exams !!

1. 10 machines can wash 20 cars in 6 hours. In how many hours can 15 machines wash 40 cars?
A) 8
B) 7
C) 15
D) 12
E) 6
A) 8
Explanation:

Washing cars is a work, so
M1*H1*W2 = M2*H2*W1
10*6*40 = 15*H2*20
Solve, H2 = 8 hrs

2. To build a house, 5 men take 60 days working 8 hours each day. In how many days 2 such houses can be built by 8 men working 10 hours each day?
A) 75
B) 50
C) 20
D) 60
E) None of these
D) 60
Explanation:

Building 1 house is 1, 2 houses is 2, so
M1*D1*H1*W2 = M2*D2*H2*W1
5*60*8*(2) = 8*D2*10*(1)
Solve, D2 = 60

3. 2 men and 4 women can complete a job in 5 days. Also same job can be completed by 3 men and 8 women in 3 days. In how many days, twice the job can be completed by 3 men and 3 women?
A) 4
B) 8
C) 10
D) 8.5
E) 13
B) 8
Explanation:

2m + 4w = 5D, so 10m + 20w = 1D
3m + 8w = 3D, so 9m + 24w = 1D
So, 10m + 20w = 9m + 24w
Solve, 1m = 4w
From 1st equation(2m + 4w = 5D), 2*4w + 4w = 5D, or 12 women can do in 5 days, so 1 women in 12*5 = 60 days.
Now 3m+3w = 3*4w + 3w = 15 w
1 women in 60 days, so 15 women in 60/15 = 4 days
But we are required to find twice work, so 15 women 1 work in 4 days so twice work in 8 days

4. A job that can be completed by 2 men and 6 women in 10 days will be completed by 5 men and 15 women in how many days?
A) 2
B) 3
C) 5
D) 4
E) Cannot be determined
D) 4
Explanation:

2m + 6w = 10 D
Or 2(1m + 3w) = 10D
Or 1m + 3w = 20D
So 5(1m + 3w) = 20/5
Or 5m + 15w = 4D

5. There is sufficient food for 40 men for a 15 days picnic. If after 6 days 4 men leave, how many more days can the remaining men intake food?
A) 8
B) 5
C) 10
D) 1
E) 3
D) 1
Explanation:

After 6 days, now food is left for 40 men for (15-6) = 9 days, now same food is eaten by (40-4) = 36 men, let it last for x days, so
40*9 = 36*x
Solve, x = 10
The food which was to last for 9 days for 40 men, now will last for 10 days for 36 men, so extra 1 day.

6. A job is completed by 5 men or 7 women in 40 days, then in how many days thrice the job as previous will be completed by 5 men and 3 women?
A) 27
B) 28
C) 38
D) 84
E) 90
D) 84
Explanation:

5 m or 7 w
5m + 3w
Cross multiply and put in denominator
Days = 40*5*7/ [5*3 +7*5] = 28
so for thrice work, days = 28*3

7. 10 women completed 2/7th of work in 18 days working 6 hours each day. After this 5 women left and 2 men joined. In how many days working same number of hours, the remaining work will get completed if 1 man is equal to 2 women?
A) 50
B) 55
C) 70
D) 58
E) 62
A) 50
Explanation:

Remaining work = 1 – 2/7 = 5/7
After 18 days, 5 women left and 2 men joined so 4 women joined (1m = 2w), now number of women is 5+4 = 9, so
10*18*6*(5/7) = 9*D2*6*(2/7)
Solve, D2 = 50

8. 20 carpets are to weave by 40 women in 50 days working 8 hours per day. After 20 days, order of 6 more carpets came. To complete the total work on time, how many more hours per day they will have to work?
A) 2
B) 4
C) 5
D) 10
E) 12
B) 4
Explanation:

First find the number of carpets weave in first 20 days, after which order of more carpets came. So,
In 50 days, 20 carpets, so in 20 days 20*20/50 = 8 carpets
So in remaining 30 days, (20-8) = 12 carpets can be weave working 8 hrs each day
Now number of carpets is (12+6) = 18, let no of hours is x, so
H1*W2 = H2*W1
8*18 = x*12
Solve, x = 12 hrs
So more hrs = 12-8 = 4 hrs

9. A work is to completed. 10 men started the work and completed 1/6th of the work in 5 days working 3 hrs each day. 2 more men are employed. In how many days will the total number of men complete four times work as before working 5 hours each day?
A) 12
B) 18
C) 10
D) 20
E) 15
C) 10
Explanation:

M2 = (10+2) = 12 men, W2 = 4*(1/6) = 4/6
So
10*5*3*(4/6) = 12*D2*5*(1/6)
Solve, D2 = 10

10. 2 men or 4 women or 5 children can complete a piece of work in 38 days. In how many days will 1 man, 1 woman and 1 child complete the same work?
A) 20
B) 40
C) 36
D) 42
E) None of these
B) 40
Explanation:

2 men or 4 women or 5 children = 38 D
So 1m + 1w + 1c = 38*2*4*5/(2*4 + 4*5 + 5*2)

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