Average – Set 4

2) The mean of 5 observations is 60, the mean of 10 observations is 30 and the mean of 15 observations is 20. The mean of all the 30 observations is-?

5) In the first 10 overs of a cricket game, the run rate was only 3.2. What should be the rate in the remaining 40 overs to each the target of 282 runs?

6) Of four numbers whose average is 60, the first is one-fourth of the sum of the last three. The first number is -?

7) Average of ten positive numbers is

. If each number is increased by 10%, then

-?

8) The average age of all the students of a class is 18 years. The average age of boys of the class is 20 years and that of the girls is 15 years. If the number of girls in the class is 20, then find the number of boys in the class.?

9) In a group of 120 people, one-fifth are men, one-fourth are women and the rest children. The average age of women is five-sixth of the average age of men. Average age of children is one-fourth of the average age of men. If average age of men is 60 years, what is the average age of the group?

10) In a certain factory there are five workers A, B, C, D and E. A can complete a work in 4 minutes, B in 5 minutes, C in 6 minutes, D in 10 minutes and E in 12 minutes. The average number of units of work completed per worker per minute will be?

11) The average temperature of the town in the first four days of month was 58 degrees. The average for the second, third, fourth and fifth days was 60 degrees. If the temperature of the first and fifth days were in the ratio 7 : 8, then what is the temperature on the fifth day?

12) The average price of 10 books is Rs. 12 while the average price of 8 of these books is Rs. 11.75. Of the remaining two books, if the price of one book is 60% more than the price of the other, what is the price of each of these two books?

13) The average of 6 observations is 45.5. If one new observation is added to the previous observations, then the new average becomes 47. The new observation is-?

14) A library has an average of 510 visitors on Sundays and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is-?

15) 16 children are to be divided into two groups A and B of 10 and 6 children. The average percent marks obtained by the children of group A is 75 and the average percent marks of all the 16 children is 76. What is the average percent marks of children of group B ?

16) The average of five consecutive odd numbers is 95. What is the fourth number in the descending order?

17) The average weight of 16 boys in a class is 50.25 kgs and that of the remaining 8 boys is 45.15 kgs. Find the average weight of all the boys in the class?

18) A, B, C and D are four consecutive even numbers respectively and their average is 65. What is the product of A and D?

19) The average of the first nine prime numbers is-?

20) The average of 11 numbers is 10.9. If the average of the first six numbers is 10.5 and that of the last six numbers is 11.4, then the middle number is 😕

21) The average of 80 boys in a class is 15. The average age of a group of 15 boys in the class is 16 and the average age of another 25 boys in the class is 14. What is the average age of the remaining boys in the class?

22) The batting average for 40 innings of a cricket player is 50 runs. His highest score exceeds his lowest score by 172 runs. If these two innings are excluded, the average of the remaining 38 innings is 48 runs. The highest score of the player is?

23) The average mark of student in 4 subjects is 75. If the student obtained 80 marks in the fifth subject, then the new average is-?

24) If the average of 5 numbers is 10, the number which should be added to make the average 12 is-?

25) A car owner buys petrol at Rs. 17, Rs. 19 and Rs. 20 per litre for three consecutive years. Compute the average cost per litre, if he spends Rs 6460 per year?

26) In an examination, a pupil’s average mark was 63 per paper. If he had obtained 20 more marks for his Geography paper and 2 more marks for his History paper, his average per paper would have been 65. How many papers were there in the examination?

29) Out of three numbers, the first is twice the second and is half of the third. If the average of the three numbers is 56, then difference of first and third numbers is?

30) The average marks of a student in 8 subjects is 87. Of these, the highest marks are 2 more than the one next in value. If these two subjects are eliminated, the average marks of the remaining subjects are 85. What are the highest marks now obtained by him?

31) A school has 4 sections of chemistry in Class X having 40, 35, 45 and 42 students. The mean marks obtained in Chemistry test are 50, 60, 55 and 45 respectively for the 4 sections. Determine the overall average of marks per student?

33) A grocer has a sale of Rs. 6435, Rs. 6927, Rs. 6855, Rs. 7230 and Rs. 6562 for 5 consecutive months. How much sale must he have in the sixth month so that he gets an average sale of Rs. 6500?

34) The average price of three items of furniture is Rs. 15000. If their prices are in the ratio 3 : 5 : 7, the price of the cheapest item is-?

35) The average of odd numbers up to 100 is?

36) The average age of 30 students in a class is 15 years. If 6 students of this class have the average age of 16 years, then the average age of the remaining 24 students would be-?

37) While calculating the average of a batsman as 36 in 100 matches that he played, one of the scores 90 was incorrectly noted as 40. The percentage error is-?

38) The average of 6 observations is 45.5. If one new observation is added to the previous observations, then the new average becomes 47. The new observation is-?

39) In Arun’s opinion, his weight is greater than 65 kg but less than 72 kg. His brother does not agree with Arun and he thinks that Arun’s weight is greater is that 60 kg but less than 70 kg. His mother’s view is that his weight cannot be greater than 68 kg. If all of them are correct in their estimation, what is the average of different probable weights of Arun?

40) The average of 7 consecutive numbers is 20. The largest of these numbers is-?

41) A pupil’s marks were wrongly entered as 83 instead of 63. Due to that the average marks for the class got increased by half. The number of pupils in the class is-?

42) If the arithmetic mean of seventy-five numbers us calculated, it is 35. If each number is increased by 5, then mean of new numbers is:?

43) A student obtained 60, 75 and 85 marks respectively in three monthly examinations in Physics and 95 marks in the final examination. The three monthly examinations are equal weighted whereas the final examination is weighted twice as much as a monthly examination. His average marks in physics are-?

46) The average of 50 numbers is 38. If the numbers 45 and 55 are discarded, then the average of the remaining numbers is-?

47) The average of two numbers is 6.5 and square root of their product is 6. What are the numbers?

48) The mean of the first ten even natural number is-?

49) The average expenditure of a man for the first five months of a year is Rs. 5000 and for the next seven months it is Rs. 5400. He saves Rs. 2300 during the year. His average monthly income is-?

50) In a class there are 32 boys and 28 girls. The average age of the boys in the class is 14 years and the average age of the girls in the class 13 years. What is the average age of the whole class (rounded to two digits after decimal) ?