1. The average of 21 numbers is 12. The average of the first 11 numbers is 9 and the average of the last 11 numbers is 15. What is the value of the middle number?
2. The average salary of all workers in a workshop is Rs.12000. The average salary of 7 technicians is Rs.15000 and the average salary of the rest is Rs.9000. The total number of workers in the workshop is
4. Seven years ago, the average age of A, B and C was 51 years. If A is 3 years older than B and B is 3 years older then C then the present ages of A, B and C are ( in year)
5. Nine students of a class contribute a certain sum of money. Seven of them gave Rs. 50 each and the other two gave respectively Rs. 50 and Rs. 90 more than the others. The average contribution of the class of 9 students is
7. In a class of 39 students there are 26 girls. The average weight of these girls is 42 Kgs and average weight of the full class is 48 kgs. What is the average weight (in kgs) of the boys of the class?
8. A factory buys 7 machines. 2 Machine A, 2 Machine B and rest Machine C. Prices of the machines are Rs 95000, Rs 75000 and Rs 43000 respectively. Calculate the average cost of these machines?
10. The average weight of Shivshankar, Gopesh and Reena is 97 kg. If the average weight of Shivshankar and Gopesh is 93 kg and that of Gopesh and Reena is 82 kg, then the weight of Gopesh is