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

What is the average age of D, R and S?

How many pairs of twin primes are there between the integers 1 to 100? 

An amount doubles itself in 5 years simple interest. What is the rate of interest per year?

Find value of $$ {^3\sqrt{\sqrt{0.000729}}}+^3{\sqrt{0.008}}$$

What is the Highest Factor of $$ {2^{3}×{3^{5}}} and \ {2^{3}×{3^{5}}}$$ ?

If the circumradius of an equilateral triangle ABC is 8 cm, then what is the height of the triangle?

A and B can do a work in 18 and 24 days respectively. They worked together for 8 days and then A left. The remaining work was finished by B in 

X and Y are centres of circles of radius 9 cm. and 2 cm respectively XY=17 cm. Z is the centre of a circle of radius r cm which touches the above circles externally. Given that - ∠xzy = 90^o the value of r is -