# Time and work 7

Welcome to aptitude tricks
Example 2: If a person can complete his work in 5days. What will be his efficiency?
Solution: Number of days a person take to complete his work = 5
⇒ He is doing 1/5 th work per day (converted into fraction)
Convert it into percentage:
100/5 = 20%
Therefore, his efficiency is 20%.
Summarizing, If a person can do his job in n days, efficiency will be
Efficiency = %
Note: Negative efficiency cancels the positive efficiency
For Example: Positive efficiency = 5%
Negative efficiency = 1.5%
Net efficiency = 5- 1.5 = 3.5%
As we all know, in competitive exams time management is very important. I suggest you to learn the
fractions till 15.
Number of days required to
complete work
Work/Day Efficiency (%)
N 1/n 100/n
1 1 100
2 1/2 50
3 1/3 33.33
4 1/4 25
5 1/5 20
6 1/6 16.66
7 1/7 14.28
8 1/8 12.5
9 1/9 11.11
10 1/10 10
11 1/11 9.09
12 1/12 8.25
13 1/13 7.69
14 1/14 7.14
15 1/15 6.66
Example 3: A can do a job in 10 days. B can do a job in 5 days. In how many days they can complete
the job if they work together?
Solution: Consider the above table
A’s efficiency = 10%
B’s efficiency = 20%
A+ B efficiency = 10 + 20 = 30%
This means, In one day A and B together can do 30% of work.
Therefore, Number of days A and B together take to do 100% of work =
⇒3.33 days