The average weight of P and his three friends is 55 kg. If P is 4 kg more than the average weight of his three friends, what is P's weight (in kg)?

The average of all the numbers between 6 and 50 which are divisible by 5 is

The average age of 6 members of a family is 25 years. If the youngest member of the family is 15 years, old then what was the average age (in years) of the family at the time of the birth of the youngest members?

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 

The average of ten numbers is 72. The average of the first four numbers is 69 and that of the next three number is 74. The 8^th number is 6 more than the 9^th number and 12 more than the 10^th number. What is the average of the 8^th and 9^th numbers?

The average of 19 numbers is 24. If each number is multiplied by 3, what is the new average?

The average weight of three men A, Band C is 84 kg. D joins them and the average weight of the four becomes 80 kg. If E whose weight is 3 kg more than that of D, replaces A, the average weight of B, C, D and E becomes 79 kg. The weight of A is: 

While purchasing one item costing Rs.400, one has to pay sales tax at 7 % and on another costing Rs. 6400, the sales tax was 9%. The percentage of sales tax one has to pay, taking these items together on an average is: