A sum amounts to ₹ 6480 in 4 years and ₹ 9600 in 8 years when it is compounded annually. Find the sum?

The average weight of 15 oarsmen in a boat is increased by 1.6 kg when one of the crews, whose weighs 42 kg is replaced by a new man. Find the weight of the new man (in kg). 

The present ages of two persons are 36 and 50 years respectively. If after n years the ratio of their age will be 3 : 4, then the value of n is 

If $${x}^2+{y}^2x+1=0$$ then the value of $$x^{31}+y{35}$$ is

Direction: The following graph shows the number of boys and girls in Class V, Class VI, Class VII and Class VIII. Study the graph and answer the question.

Which class has the maximum number of students?

If the height of a cylinder is increased by 15% and the radius of its base is decreased by 10%, then by what percent will its curved surface area change?

Direction: Study the following information to answer the questions.

On Wednesday, in hotel A, 30% of male customers and 70% of female customers were from Town X. what was the number of customers in hotel A from town X on Wednesday?

A person invested a sum of Rs. 18,600 at x% per year and another sum that is twice the former at (x+2)% per year, both at simple interest. If the total interest earned on both investments for $$ {3{1\over 2}}$$ years is Rs.23,110.50, then the rate of  interest per year on the second investment is: