The average age of 30 boys in a class is 15 years. One boy, aged 20 years, left the class, but two new boys came in his place whose age differs by 5 years. If the average age of all the boys now in the class becomes 15 years, the age of the younger newcomer is: 

Average of 11 number is 30. If the average of first 10 numbers is 22, then find the 11th number?

The average of five numbers is 49. The average of the first and the second numbers is 48 and the average of fourth and fifth numbers is 28. What is the third number?

The average of 20 numbers is 32. If two numbers are 29 and 31, then what is the average of the remaining numbers (correct up to two decimals)? 

In a school with 600 students the average age of the boys is 12 years and that of the girl is 11 years. If he average age of the students is 11 years 9 months, then the number of girls in the school is

Rohit purchased 12 kg of oranges for a total price of ₹480 and 18 kg of guavas at 30 per kg. What cost of the fruits purchased by Rohit?