The average marks of 42 students in an examination, were 64. Later it was found that the marks of three students were misread as 72, 58 and 44 instead of the actual marks 64, 42 and 26 respectively. What are the correct average marks?

A batsman makes a score of 87 runs in the 17^th match and thus  increases his average by 3. Find his average after 17^th match.

The average of x numbers is 48. If of the numbers are increased by 51 each and remaining are decreased by 71 each, then what is the new average?

In an examination, 40% of the candidates write their answers in Urdu and the rest in Marathi. The average marks of the candidates writing in Urdu is 74 and the average marks of the candidates writing in Marathi is 77. What are the average marks of all the candidates? 

The average weight of a group of 20 boys was calculated to be 89.4 kg and it was later discovered that one weight was misread as 78 kg instead of 87 kg. The correct average weight is 

A fruit seller sold big, medium and small-sized apples for Rs.15, Rs. 10, and Rs. 5, respectively. The total number of apples sold were in the ratio 3: 2: 5. Find the average cost of an apple.