Quantitative Aptitude - Arithmetic Ability Questions

The standard deviation of the set {10, 10, 10, 10, 10} is

The perimeter of a right-angled triangle is k times the shortest side. If the ratio of the other side to hypotenuse is 4 : 6, then what is the value of k?

In the following question, select the odd number from the given alternatives.

After deducting 60% from a certain number and then deducting 15% from the remainder, 1428 is left. What was the initial number?

The age of Ravi is twice the age of Prakash and three times the age of Kumar. If the age of Prakash is 24 years, then what will be the age of Kumar after 4 years ?

Length of two trains are 150 m and 200 m respectively and the ratio (shorter: longer) of their speed is 2 : 5. If they cross each other in opposite direction in 15 second then in what time faster train will overtake the slower train.

What is the average of first 19 odd numbers?

A man travels 420 kilometres in, partly by rail and partly by steamer. He spends 8 hours more time on steamer. If the velocity of the steamer is 35 km/hr and the velocity of rail is 65 km/hr, how much distance does he cover by steamer?