$A$ money lender claims to lend money at the rate of $10 \%$ per annum simple interest. However,he takes the interest in advance when he lends a sum for one year. At what interest rate does he lend the money actually?

Alipta received some amount of money from her father. In how many $years$ will the ratio of the money (principal) and the interest obtained from it be $10: 3$ at the rate of $6 \%$ simple interest per annum?

The simple interest on ₹ $500$ at $6 \%$ per annum from $May$ $3^{rd}$ to $July$ $15^{th}$ in the same year is (in ₹):

Ram deposited a certain sum of money in a company at $12 \%$ per annum simple interest for $4$ years and deposited an equal amount in a fixed deposit in a bank for $5$ years at $15 \%$ per annum simple interest. If the difference in the interest from the two sources is $Rs. 1350$,then the sum (in $Rs.$) deposited in each case is:

Mrs. Sushma lent out an amount of $Rs. 3000$ at $4 \%$ p.a. and some other amount at $5 \%$ p.a. If at the end of the year she received $Rs. 138$ as total interest,what amount (in $Rs.$) did she lend out at $5 \%$ p.a.?

The rate percent per annum at which ₹ $1200$ amounts to ₹ $1440$ in $4$ years is: