Correct Answer - Option 2 : 12
Given:
7 experts and 5 trainees can complete a job in 9 days
4 experts and 15 trainees can complete it in 12 days
Formula used:
Total work = Men × Day
Calculation:
Let efficiency of expert be E and efficiency of trainees be T
⇒ (7E + 5T) × 9 = (4E + 15T) × 12
⇒ 63E + 45T = 48E + 180T
⇒ 63E – 48E = 180T – 45T
⇒ 15E = 135t
⇒ E/T = 9/1
So, efficiency of experts is 9 and trainees is 1.
Then, total work
⇒ (7E + 5T) × 9
⇒ (7 × 9 + 5) × 9
⇒ (63 + 5) × 9
⇒ 612
Then, 5 Expert and 6 trainees need to complete 612 unit work is
⇒ (5E + 6T) × Days = 612
⇒ (5 × 9 + 6) × Days = 612
⇒ 51 × Days = 612
⇒ Days = 612/51
⇒ Days = 12
∴ 5 experts and 6 trainees need to complete the job in 12 days