Quantitative Aptitude - Arithmetic Ability Questions

What is the curved surface area (in cm²) of a hemisphere of diameter 42 cm?

If X and Y are the two digits of the number 347XY such that the number is completely divisible by 80, then what is the value of X + Y?

The average of 10 numbers is 30. If at the time of calculation one number was wrongly taken as 36 instead of 69, then what will be the correct average?

Find the average of all prime numbers from 1 to 50.

Find the missing number?

Simplify (2/7 + 3/5) / (2/5 + 2/7)

If three successive discounts of 20%, 30% and 40% are given, then what will be the net discount (in percentage)?

Sin6A + Cos6A - 1 is equal to