Maths - Average 1. Find the average of first 50 natural numbers. a. 50 b. 50.5 c. 60 d. None of these 2. Find the average of first 20 multiples of 7. a. 140 b. 50.5 c. 73.5 d. None of these 3. The average of four consecutive even numbers is 29. The least number of these numbers is a. 26 b. 28 c. 30 d. None of these 4. The average of 25 results is 18. The average of first twelve of them is 14 and that of last 12 is 17. The thirteenth result is a. 78 b. 79 c. 80 d. None of these 5. The average of all odd numbers up to 100 is a. 49 b. 50 c. 100 d. None of these 6. The average of five consecutive odd numbers is 59. What is the difference between the highest and lowest number? a. 2 b. 4 c. 6 d. 8 7. The mean of 12,22,32,42,52,62,72 is a. 10 b. 20 c. 30 d. 40 8. The average marks of three batches of 55, 60 and 45 students respectively is 50, 55 and 60, then the average marks of all the students is a. 53.33 b. 54.68 c. 55 d. None of these 9. The average of 50 numbers is 30. If two numbers, 60 and 48 are discarded, then the average of remaining numbers is a. 27 b. 29 c. 30 d. None of these 10. The average age of a class of 35 students is 14.8. A new student joins the class and the average becomes 14.9 years. The age of new comer is a. 18.4 b. 16.3 c. 17.4 d. None of these 11. Of the four numbers, whose average is 60, the first is one-fourth of the sum of the last three. The first number is a. 15 b. 45 c. 48 d. 60.25 12. If the average mean of 49 numbers is calculated, it is 35. If each number is increased by 5, then mean of new numbers is a. 35 b. 40 c. 50 d. None of these 13. The mean of 50 observations was 36. It was found later that an observation 48 was taken as 23. The correct new mean is a. 35.2 b. 36.1 c. 36.5 d.39.1 14. The average monthly salary of A, B and C is Rs. 4000 and that of B, C and D is Rs. 5000. The actual salary of A is Rs. 2750. The actual salary of D is a. 5750 b. 5870 c. 5780 d. None of these 15. There are 30 students in a class. The average age of first 10 students is 12.5 years. The average age of next 20 students is 13.1 years. The average age of the students of whole class is a. 12.5 b. 12.5 c. 12.8 d. 12.9 16. The average weight of a class of 24 students is 35 kg. If the weight of the teacher be included, the average rises by 400g. The weight of the teacher in kg is a. 45 b. 50 c. 53 d. 55 17. A batsman average score for a number of innings was 21.75 per innings. In the next three innings he scored 23, 34 and 37 runs and his average for all the innings was raised by 1.25. How many innings in all did he play? a. 20 b. 23 c. 26 d. 29