In what time (in $years$) will ₹ $1200$ become ₹ $1344$ at $6 \%$ per annum simple interest?

The rate of simple interest (in $\%$) for which a sum of money becomes $5$ times of itself in $8$ years is:

In what time (in $years$) will a sum of money double itself at the rate of $20 \%$ per annum simple interest?

Mr. Irani borrowed a sum of ₹ $10000$ from a finance company for $6$ years at $8 \%$ per annum. The amount (in ₹) returned by Mr. Irani to the finance company is:

The simple interest on a sum for $8$ years is ₹ $47500$. The rate of interest is $10 \%$ per annum for the first $5$ years and $15 \%$ per annum for the next $3$ years. What is the value (in ₹) of the sum?

Simple interest on a certain sum is $\frac{16}{25}$ of the sum. If the rate per cent and time (in years) are equal,then the rate per cent is: