CAT (QA) PYQs

Gopal borrows Rs. $X$ from Ankit at $8 \%$ annual interest. He then adds Rs. $Y$ of his own money and lends Rs. $X+Y$ to Ishan at $10 \%$ annual interest. At the end of the year, after returning Ankit's dues, the net interest retained by Gopal is the same as that accrued to Ankit. On the other hand, had Gopal lent Rs. $X+2Y$ to Ishan at $10 \%$, then the net interest retained by him would have increased by Rs. $150$. If all interests are compounded annually, then find the value of $X+Y$.

Alex invested his savings in two parts. The simple interest earned on the first part at $15 \%$ per annum for $4$ years is the same as the simple interest earned on the second part at $12 \%$ per annum for $3$ years. Then, the percentage of his savings invested in the first part is

Aman invests Rs $4000$ in a bank at a certain rate of interest, compounded annually. If the ratio of the value of the investment after $3$ years to the value of the investment after $5$ years is $25: 36$, then the minimum number of years required for the value of the investment to exceed Rs $20000$ is