If  $$n+{2\over 3}n+{1\over2}n+{1\over7}n=97$$ then the value of n is : 

The average of 11 numbers is 7. If each number is doubled, what will be the new average of the numbers?

A shopkeeper charges his customers 15% above the cost price, if a customer has bought a sofa-set for 9039, then for how much did the shopkeeper buy it?

A can do 2% of a work in 4 days, B can do $$33{1\over 3}\%$$ of the same work in 10 days. They worked together for 9 days. C completed the remaining work in 6 days. B and C together will complete 75% of the same work in :

Directions : The Bar Graph given here shows the population (in crores) of India in various census years. Observe the graph and answer the question based on it.

The per cent increase in population from 1971 to 1981 is

if $${secθ={a\over b},b≠0,then \ {{1-tan^2θ}\over 2-sin^2θ}  }=?$$

12 persons can do a piece of work in 4 days. How many persons are required to complete 8 times the work in half the time?

Find the area of the triangle whose sides are 5 cm, 12 cm and 13 cm.