C and D invested Rs. 'Y' and Rs. 3600 respectively. If after 6 months, C increases his investment by Rs. 1200, and the ratio of the profit share of C to D after a year is 19:15, then find the initial investment of C (in Rs).

Correct option is C

Information Given:
C and D invested Rs. 'Y' and Rs. 3600 respectively.
After 6 months, C increases his investment by Rs. 1200, and the ratio of the profit share of C to D after a year is 19:15.
Formulas Used:
Profit share = Investment × Time
Basic Explanation:
The profit-sharing ratio = Y×6+(Y+1200)×6 :3600×12
= 2Y + 1200 : 7200
ATQ,
$$\frac{2Y + 1200}{7200} = \frac{19}{15}$$​
2Y + 1200 = 9120
2Y = 7920
Y = 3960