Correct Answer - Option 1 : 7

**Given:**

Time taken by a man to complete a work = 15 days

Time taken by 2 women to complete the work = 45 days

Time taken by 4 boys to complete the work = 18 days

**Concept Used:**

Efficiency = 1/Time taken

If "n" persons can complete the task in x days,

then 1 person can complete the same task in nx days.

**Calculation:**

Let the number of boys required for assisting be x

Time taken by a woman to complete the work = 45 × 2 = 90 days

Time taken by a boy to complete the work = 18 × 4 = 72 days

Hence, we can calculate the efficiency of 5 men, 6 women and x boys as:

⇒ (5/15) + (6/90) + (x/72) = (1/2)

⇒ (1/3) + (1/15) + (x/72) = (1/2)

⇒ (2/5) + (x/72) = (1/2)

⇒ x/72 = (1/2) – (2/5)

⇒ x = 7.2

**∴ The required number of boys is approximately 7**