Average between two numbers

The difference between two numbers is 9 and the difference between their squares is 207. The numbers are ,

The average marks of 48 students in a class is 45. the average marks of the boys in the class is 40 and average marks of the girls in the class is 50. what is the ratio between the numbers of boys and the number of girls in the class ?

The average of five numbers is 58. The average of the first two numbers is 48.5 and the average of last two numbers is 53.5 .What is the third number?

The average of five numbers is 58. The average of first two numbers is 48.5 and the average of last two numbers is 53.5. Find the third number.

The sum of five numbers is 290. The average of the first two numbers is 48.5 and the average of last two numbers is 53.5. What is the third number?

The sum of five numbers is 290. The average of the first two numbers is 48.5 and the average of last two numbers is 53.5. What is the third number?