A car travel to a place 150 km away at an average speed of 50 km/hr and returns it 30 km/hr. What is the average speed of the whole journey?

A batsman makes a score of 87 runs in the 17^th match and thus  increases his average by 3. Find his average after 17^th match.

The average age of 30 students is 9 years. If the age of their teacher is included, the average age become 10 years. The age of the teacher ( in years ) is

The average of 5 consecutive integers starting with ‘M’ is ‘K’. What is the average of 6 consecutive integers stating with (m+1)?

The average weight of 15 oarsmen in a boat is increased by 1.6 kg when one of the crews, whose weighs 42 kg is replaced by a new man. Find the weight of the new man (in kg). 

The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, then the weight (in kg) of B is 

A man spends Rs. 1800 monthly on an average for the first four months and Rs. 2000 monthly for the next eight months and saves Rs. 5600 a year. His average monthly income is

Find the average of all prime numbers between 30 and 50.