There are 10 balls, some of them are red and the others white. The average cost of all the balls is Rs. 28, average cost of red balls Rs. 25 and that of white balls is Rs. 30, the number of white balls is: 

Some students (only boys and girls) from different schools appeared for an Olympiad exam. 20% of the boys and 15% of the girls failed the exam. The number of boys who passed the exam was 70 more than that of the girls who passed the exam'. A total of 90 students failed. Find the number of students that appeared for the exam.

The average weight of five persons sitting in a boat is 38 kg. The average weight of the boat and the persons sitting in the boat is 52kg. What is the weight of the boat?

What is the average of all numbers between 100 and 200 which are divisible by 13?

The average of 5 numbers is 27. If one number is excluded, the average becomes 25. The excluded number is: 

The average monthly expenditure of a family for the first four months is ₹ 2570, for the next three months ₹ 2490 and for the last five months ₹3030. If the family saves ₹ 5320 during the whole year, the average monthly income of the family during the year is-

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 monthly savings of Shifa for the first 5 months is Rs. 2120, for the next 3 months is Rs. 4260 and for the remaining months of the year is Rs. 3140. Now, the average monthly expenditure for the complete year is Rs. 11000. Find the total income of the year