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

The angle of elevation of the top of a tree 220 metres high from two points lies on the same plane are 30° and 45°. What is the distance (in metres) between the two points?

A semi-circular sheet of metal of diameter 28 cm. is bent into an open conical cup. The depth of the cup is approximately 

A man invested a certain sum in scheme A at 15% p.a. for 2 years and earned Rs 1950 as simple interest. He increased his sum by Rs. ‘x’ and invested in another scheme B at 10% p.a. C.I. for 2 years and received Rs. 1680 as compound interest. Find the value of ‘x’. 

The least number, which is a perfect square and is divisible by each of the numbers 16, 20 and 24 is 

A dozen pairs of socks quoted at ₹ 80 are available at a discount of 10%. How many pairs of socks can be bought for 24? 

In a triangle, lengths of all the three medians are 9 cm, 12 cm. and 15 cm respectively. Then what will be the area of the triangle?

Two numbers are 30% and 37% lesser than a third number. By how much percent is the second number to be enhanced to make it equal to the first number?