Quantitative Aptitude - Arithmetic Ability Questions

A man can row upstream at 12 km/hr and downstream at 18 km/hr. The man's rowing speed in still water is

A man can row his boat at a speed of speed of 4 kmph and he finds that the time taken rowing upstream is double to that taken downstream. Find the speed of the stream (in kmph).

The area of the largest triangle that can be inscribed in a semicircle of radius 6m is

In a triangle PQR, PX, QY and RZ be altitudes intersecting at O. If PO = 6 cm, PX = 8 cm and QO = 4 cm, then what is the value (in cm) of QY?

If 3n = 2187, then the value of n is:

P bought an article for Rs. 1600 and sold it at a profit of 10%. What would have been the increase in the profit percent if it was sold for Rs. 1840?

Vikram and Vivek can finish a work in 50 days. They worked together for 20 days and then left. How much work has been done by them?

The average of 19 consecutive even integers is 50. The highest of these integers is