Correct Answer - Option 3 : 6 months

Given:

Investment of A = Rs. 9000

Investment of B = Rs. 7500

Ratio of their profit = 12 : 5

Concept used:

Partnership & Ratio method

Calculation:

Let the time period for B's investment be x

So, (9000 × 12)/(7500 × x) = 12/5

(90 × 12)/(75 × x) = 12/5

X = (90 × 12 × 5)/(12 × 75)

X = 6 months

**∴ Time for which B invested in the business is 6 months**