CHAIN RULE-PART2

*14 pumps of equal capacity can fill a tank in 6 days, if the tank has to be filled in 4 days. The number of extra pumps needed is : Ans 7

Difficulty Level : Easy Moderately easy Difficult

Basic Formula:

Indirect Proportion



Answer with Explanation:
Number of pumps Number of days
14 6
x 4

Let x be the pumps needed
6 X 14 = 4 X x
X = 84/4 = 21
X = 21 pumps

Already there are 14 pumps available
Extra pumps = 21 - 14 = 7

*If 6 men working 7 hours a day can plough a field in 48 days, in how many days will 14 men working 12 hours a day plough the same field ? Ans: 32

Difficulty Level : Easy Moderately easy Difficult

Basic Formula:
Indirect Proportion

More men, less days – Indirect proportion
More time, Less days - Indirect proportion

Answer with Explanation:
Step 1 Number of men Number of Hours Number of days
10 7 8
8 12 x

Step 2
6 X7 X 48 = 14 X 12 X x
X =
X = 12 days

*If 80 lamps can be lighted 5 hours per day for 10 days for Rs.21.24 then the number of lamps which can be lighted 4 hours daily for 30 days for Rs.76.50 is Ans:120

Difficulty Level : Easy Moderately easy Difficult

Basic Formula:
Less hours, More lamps – Indirect proportion
More days, less lamps - Indirect proportion
More money, more lamps - Direct Proportion

Answer with Explanation:
Number of hours Days Amount Lamps
5 10 21.24 80
4 30 76.50 x

5 X 10 X 76.50 X 80 = 4 X 30 X 21.24 X x
x =
x = 120 lamps

*If 12 carpenters, working 6 hours a day can make 460 chairs in 24 days, how many chairs will 18 carpenters make in 36 days, each working 8 hours a day ? Ans: 1380

Difficulty Level : Easy Moderately easy Difficult

Basic Formula:
More carpenters, more chairs - Direct proportion
More hours, more chairs - Direct proportion
More days, more chairs - Direct proportion

Answer with Explanation:
Number of carpenters hours Days chairs
12 6 24 460
14 8 36 x
12 X 6 X 24 X x = 18 X 8 X 36 X 460
x =
x = 1380 Chairs

*400 person working 9 hours per day complete 1/4th of the work in 10 days. The number of additional persons, working 8 hours per day required to complete the remaining working in 20 days is Ans: 275

Difficulty Level : Easy Moderately easy Difficult

Basic Formula:
Less hours, More men required - Indirect Proportion
More days, less men required - Indirect Proportion
More work, More men required - Direct Proportion



Answer with Explanation:

Let x be the number of persons completing the work in 20 days
Step 1 work done = ¼, Remaining work = 1 – ¼ = ¾
Hours hours Days men
9 1/4 10 400
8 3/4 20 x
Step 2
9 X ¾ X 10 X 400 = 8 X ¼ X 20 X x
X = = 675
Already available persons = 400
Additional persons = 675 – 400 = 275