In triangle ABC a straight line parallel to BC intersects AB and AC at D and E respectively. If AB = 2AD then DE : BC is

Direction: Study the following information and answer the related questions. P, Q, R, S, T, A, B, C, D and E are employees of a company. A table shows the average age of any two employees of the company. The average age of A and B is 27.5.
i.e. average age of A & P is given as (A+P)/2=39.5

If age of P and Q is decreased by 50% and age of A and B is increased by 20%, what will be the ratio of ages of P, Q, R, S and T together to the ages of A, B, C, D and E together?

If $$ {x+{1\over x}}=3$$ then find the value of $$ {x^2}-{1\over {x^2}}$$:

A solid sphere of diameter 7 cm is cut into two equal halves. What will be the increase (in cm.²) in the total surface area?

2,40,000 is taken as loan for three years compounded annually at 12.5 % p.a. At the end of first year, the interest is revised to 12 % p.a. The total amount to be repaid at the end of third year is:

The cost of levelling a ground in rectangular shape for a proposed garden at 80 paise per square meter is Rs.132 and the cost of fencing the same along its perimeter is Rs.78 at Rs.1.50 per meter. If the garden is extended in rectangular shape with its sides as cubes of the originally proposed garden, what will be the perimeter of the garden after extension?

Simplify : $$ {(7) ^{2} ÷(7^{1\over 2})^{4}}$$

Two guns were fired from the same place at an interval of 13 minutes but a person in a train approaching the place hears the second shot 12 minutes 30 seconds after the first. Find the speed of train if sound travels at 330 metres per second.