River is running at 2 kmph. It took a man twice as long to row up as to row down the river. The rate (in km/hr) of the man in still water is:

If the price of 5 transistors and 2 pen stands is Rs. 810, then what will be the price of 7 transistors and 9 pen stands?

An urn contains 9 blue, 7 white and 4 black balls. If 2 balls are drawn at random, then what is the probability that only one ball is white?

What is 50% of 40% of Rs. 3,450?

A and B are two taps which can fill a tank individually in 10 minutes and 20 minutes respectively. However, there is a leakage at the bottom which can empty a filled tank in 40 minutes. If the tank is empty initially, how much time will both the taps take to fill the tank (leakage is still there) ?

What is the average age of a family of five members, whose ages are 42, 49, 56, 63 and 35 years respectively?