Quantitative Aptitude - Arithmetic Ability Questions

Of the 5 numbers whose average is 78, the first is 2/11 times the sum of other 4. The first number is

ΔABC a right angled triangle has ∠B = 90° and AC is hypotenuse. D is its circumcentre and AB = 3 cms, BC = 4 cms. The value of BD is

x and y are two numbers such that their mean proportion is 9 and third proportion is 243. What is the value of x and y?

Find the odd one out among the following.

What is the unit digit of 15+25+35+...+205 ?

If Sec θ = 5/3, then what is the value of Cosec θ?

The mean of 20 observations is 19. One more observation is included and the new mean becomes 20. The 21st observation is

A solid sphere of diameter 7 cm is cut into two equal halves. What will be the increase (in cm2) in the total surface area ?