In an office, 40% of the staff is female. 70% of the female staff and 50% of the male staff are married. The percentage of the unmarried staff in the office is :

Answer: Option B

Let the total staff = 100
40% of female, i.e 40 female and 60 male
70% of female staff is married i.e. 70% of 40 female = 28
Number of unmarried female = 40 - 28 = 12
50% of male staff is married i.e 50% of 60 male = 30
Number of unmarried male = 60 - 30 = 30
Total number of unmarried staff = 12 + 30 = 42
% of unmarried staff = $$\frac{42}{100}$$ × 100   = 42%