30boysand 18 girls form agroup for social work. Düring their membership drive some boys and girls joined the group in equal number. How many members does the group have now, if the ratio of girls to boys is 7 : 11 ?

Whilesolvingamathematical problem, a Student cubed the given number and then substracted 2 from it instead of doing what was required, ie first substracting 2 from the number and then cubing it. But he got the correct answer. What was the given number ?

Giridhar invested equal sums of money in two schemes. Under Scheme A, the simple rate of interest was 15 p. c. p. a. and under Scheme B the Compound interest rate was 20 p.c.p.a. The interest after two years on the sum invested in Scheme B was Rs 45. How much is the interest earned under Scheme A after 2 years ?