Quantitative Aptitude - Arithmetic Ability Questions

The mean of 100 observations was calculated as 40. It was found later on that one of the observations was misread as 83 instead of 53. The correct mean is:

PQR is an equilateral triangle whose side is 10 cm. What is the value (in cm) of the inradius of triangle PQR?

What is the value of tanπ4+A×tan3π4+A ?

If C + 1C = 3, then what is the value of C-37+1C7?

What is the value of 23+5252-23 ?

If x - y = -9 and xy = -20, then find x2 + y2 ?

In ΔXYZ measure of angle Y is 90°. If cosecX = 17/15, and XY = 4cm, then what is the length (in cm) of side YZ?

The curved surface area and the slant height of a right circular cone are 99 sq.cm and 9 cm respectively. Find its diameter (in cm)