Quantitative Aptitude - Arithmetic Ability Questions

A cricketer, whose bowling average was 12.4 runs/wicket takes 5 wickets for 22 runs in a match, thereby decreases his average by 0.4. The number of wickets, taken by him before this match was:

Which of the following quadratic equations has real roots?

Twenty one times of a positive number is less than its square by 100. The value of the positive number is

Three pipe P, Q and R can fill a tank in 12 minutes, 18 minutesand 24 minutes respectively. The pipe R is closed 12 minutesbefore the tank is filled. In what time the tank is full?

Two circles are having radii 9 cm and 12 cm. The distance between their centres is 15 cm. What is the length (in cm) of their common chord?

The average of 10 numbers is X and one of the number is 38. If 38 is replaced with 19, then what will be the new average?

The average marks obtained by a group of 10 students were 20. One student left the group as a result of which the average of the remaining students rose to 21. But another student joined, as a result of which the average marks of the group dropped a bit and became 20.6. What were the average marks obtained by the student who left and the one who joined?

Tanya got an increment of 15% in her salary. If her enhanced salary is Rs.14,030. What was her original salary?