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.) 

The average score of top 6 batsmen of Indian cricket team in a match is 46. If the 7th batsman is included, the average becomes 50. If the 8 batsman comes and scores 34 runs, then find the ratio of the average scores of top 6 and top 8 batsmen.

A man purchased 7 bags of rice at the rate of  ₹ 800 each, 8 bags of rice at ₹ 1000  each and 5 bags of rice at the rate of  ₹ 1200 each. What is the average cost of one bag of rice?

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?

The average of 30 numbers is 40 and that of the other 40 numbers is 30. The average of all the numbers is-

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.

The average score in Mathematics of 90 students of section A and B of class IX was 63. The number of students in A were 10 more than those in B. The average score of students in A was 30% more than that of students in B. The average score of students in B is:

The mean of 9 observations is 16. One more observation is included and the new mean becomes 17. The 10th observation is