Solution :
The standard time for doing a job in minutes is given by :
Standard time = Normal time + normal time x allowance factor.
Here, it is given that ,
Allowance factor = 20%
= 0.20
Normal time of doing a a job = 12 minutes.
Therefore,
Standard time = Normal time + normal time x allowance factor
Standard time = 12 + 12 x 0.20
= 12 + 2.4
= 14.4
Thus, the standard time for doing the job is 14.4 minutes.