Jaclyn buys $50 000 worth of debentures in a company. She earns 9.5% p.a. simple interest, paid to her quarterly (that is, every 3 months). If the agreed period of the debenture was 18 months: calculate the total amount collected at the end of the term.

A sum of Rs 4000 becomes Rs 7000 in 6 years at simple interest. If the rate of interest becomes double of itself, then what will be the amount (in Rs) after 6 years?

Sachin lent out Rs 60000 in two parts, first at 4% and the second at 10% interest. The yearly average interest comes out to be 6.4%. What are the amounts (in Rs) that were lent at 4% and 10% respectively?

Rs. x invested at 8% simple interest per annum for 5 years yields the same interest as that on Rs. y invested at 7.5% simple interest per annum for 6years. Find x : y.