How many job applicants had applied if the ratio of selected to unselected was 19:17. If 1,200 less had applied and 800 less selected, then the ratio of selected to unselected would have been 1:1.

Let s and u be the no. of candidates selected and unselected respectively.

Total candidates applied = s+u

Condition 1:

Ratio of selected to unselected was 19: 17.

s/u = (19/17)

17s= 19u ——(1)

Condition 2:

If 1200 less had applied and 800 less selected, the ratio of selected to unselected would have been 1 : 1

Total candidates applied = s+u-1200

Selected candidates = s-800

Then, unselected candidates = s+u-1200 - (s-800) = s+u-1200-s+800 = u-400

(s-800)/(u-400) = (1/1)

s-800 = u-400 —-(2)

From (1),

u = (17/19)s

Substitute in (2),

s-800 = (17/19)s -400

s= 3800

u = 3400

s+u = 3800 + 3400 = 7200

The number of applicants is 7200

B is correct choice.