Aptitude - Chain Rule

Exercise :: Chain Rule - General Questions

6. 

A man completes of a job in 10 days. At this rate, how many more days will it takes him to finish the job?

A. 5
B. 6
C. 7
D.
7 1
2

Answer: Option B

Explanation:

Work done = 5
8

Balance work = 1 - 5 = 3
8 8

Let the required number of days be x.

Then, 5 : 3 = :: 10 : x     5 x x = 3 x 10
8 8 8 8

x = 3 x 10 x 8
8 5

x = 6.


7. 

If a quarter kg of potato costs 60 paise, how many paise will 200 gm cost?

A. 48 paise
B. 54 paise
C. 56 paise
D. 72 paise

Answer: Option A

Explanation:

Let the required weight be x kg.

Less weight, Less cost (Direct Proportion)

250 : 200 :: 60 : x       250 x x = (200 x 60)

x= (200 x 60)
250

x = 48.


8. 

In a dairy farm, 40 cows eat 40 bags of husk in 40 days. In how many days one cow will eat one bag of husk?

A. 1
B.
1
40
C. 40
D. 80

Answer: Option C

Explanation:

Let the required number of days be x.

Less cows, More days (Indirect Proportion)

Less bags, Less days (Direct Proportion)

Cows 1 : 40 :: 40 : x
Bags 40 : 1

1 x 40 x x = 40 x 1 x 40

x = 40.


9. 

A wheel that has 6 cogs is meshed with a larger wheel of 14 cogs. When the smaller wheel has made 21 revolutions, then the number of revolutions mad by the larger wheel is:

A. 4
B. 9
C. 12
D. 49

Answer: Option B

Explanation:

Let the required number of revolutions made by larger wheel be x.

Then, More cogs, Less revolutions (Indirect Proportion)

14 : 6 :: 21 : x       14 x x = 6 x 21

x = 6 x 21
14

x = 9.


10. 

If 7 spiders make 7 webs in 7 days, then 1 spider will make 1 web in how many days?

A. 1
B.
7
2
C. 7
D. 49

Answer: Option C

Explanation:

Let the required number days be x.

Less spiders, More days (Indirect Proportion)

Less webs, Less days (Direct Proportion)

Spiders 1 : 7 :: 7 : x
Webs 7 : 1

1 x 7 x x = 7 x 1 x 7

x = 7.