The average weight of 8 people is increased by 2 kg when a new person comes in place of the person who weighs 50 kg. What is the weight of the newcomer?

A librarian purchased 60 story books for his library. But he found that he could get 4 extra books by spending Rs. 336 more and then the overall average price per book would be reduced by Re 1. The previous average price of each book was 

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

The average of a,b,c is 20 and that of b,c,d is 25, if d=30, then the value of a is-

If (a + b): (b + c): (c + a) = 5: 6: 9 and a + b + c = 10. What is the value of c?

Average of 21 number is 36. If the average of first 12 numbers is 15, then find the average of remaining 9 number?

The average of 5 numbers, arranged in a row, is 309. The average of the first two of these numbers is 431 and the average of the last two of these numbers is 231.5. What is the value of the number at the center of the row?

In a year, the average expenditure of a family for the first 3 months, next 4 months and last 5 months is Rs 8400 per month, Rs 10080 per month, Rs 10608. Monthly and annual savings are Rs. 8640. If so, what is the average monthly income of this family?