A batsman scored 87 runs in the 21st match in his career. His average of runs per match increased by 2. What was his average before the 21st match?

12 kg of rice costing 30 per kg is mixed with 8 kg of rice costing 40 per kg. The average per kg price of mixed rice is

The mean weight of 34 students of a school is 42 kg. If the weight of the teacher be included, the mean rises by 400 grams. Find the weight of the teacher (in kg.) 

If the average weight of 6 students is 50 kg; that of 2 students is 51 kg; and that of other 2 students is 55 kg; then the average weight of all students is

A man bought 13 articles at 70 each, 15 at 60 each and 12 at 65 each. The average price per article is 

The average weight of 40 children of a class is 36.2 kg. When three more children with weight 42.3 kg, 39.7 kg and 39.5 kg join the class, the average weight of the 43 children in the class is: 

The average score of 14 students was calculated as 71. But later it was found that marks of one student were recorded as 42 instead of 56 and as 74 instead of 32 of the other. Correct average?

4 boys and 3 girls spent Rs. 120 on an average, of which boys spent Rs. 150 on the average. Then the average amount spent by the girls is.