Average Questions

The average of 7 numbers is 30. If the average of first three numbers is 25 and that of last three numbers is 35, then what is the fourth number?

The average marks of 10 students in an examination was 25. It was later found that the marks of one student had been wrongly entered as 34 instead of 43. What is the correct average?

What will be the average of all the prime numbers before 19?

The mode and median of the data 8, 6, 8, 7, 8, 6, 8, 7, 6 is

A factory buys 8 machines. 3 Machine­A, 4 Machine­B and rest Machine­C. Prices of the machines are Rs 45000, Rs 25000 and Rs 35000 respectively. Calculate the average cost (in Rs) of these machines?

The mean of marks secured by 35 students in division A of class X is 65, 45 students of division B is 61 and that of 70 students of division C is 59. What is the mean of marks of the students of three divisions of Class X?

The average marks obtained by a group of 10 students were 20. One student left the group as a result of which the average of the remaining students rose to 21. But another student joined, as a result of which the average marks of the group dropped a bit and became 20.6. What were the average marks obtained by the student who left and the one who joined?

A person purchased 10 shirts costing Rs 150 per shirt. Next day  he again purchased the shirts costing Rs 150 per shirt at a discount of Rs 30 per shirt and that day he spent a toal of Rs 1800. What is the average cost per shirt (in Rs)?