The average age of 30 students of a class is 15 years. A 20-year-old student left the class and replaced by two new students, whose age difference is 5 years. If the average age of all students is 15 years, then what will be ratio of young student to elder students. 

Average age of 6 boys is 14 years. Average age of 11 girls is 12 years. What is the average age (in years) of all boys and girls?

The average weight of a group of 20 boys was calculated to be 89.4 kg and it was later discovered that one weight was misread as 78 kg instead of 87 kg. The correct average weight is 

The average of x numbers is 48. If of the numbers are increased by 51 each and remaining are decreased by 71 each, then what is the new average?

When the average age of husband, wife and their son was 42 years, the son got married and a child was born just one year after marriage. When the child turned to be 5 years, the average age of the family becomes 36 years. What was the age of daughter-in-law at the time of marriage?

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

The average weight of P, Q and R is 93 kg. If the average weight of P and Q is 89 kg and that of Q and R average weight is 96.5 kg ,  then the weight (in kg) of Q is____.

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.