Average problems
- 1. In an examination, a pupil's average marks were 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 ?
Options- A. 8
- B. 9
- C. 10
- D. 11 Discuss
Correct Answer: 11
Explanation:
Let the number of papers be x. Then, 63x + 20 + 2 = 65x or 2x = 22 or x = 11.
- 2. 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 :
Options- A. 10.5
- B. 11.5
- C. 12.5
- D. 13.5 Discuss
Correct Answer: 11.5
Explanation:
Middle numbers = [(10.5 x 6 + 11.4 x 6) - 10.9 x 11] = (131.4 - 119-9) = 11.5.
- 3. The average age of 8 men is increased by years when two of them whose ages are 21 years and 23 years are replaced by two new men. The average age of the two new men is :
Options- A. 20
- B. 30
- C. 40
- D. 50 Discuss
Correct Answer: 30
Explanation:
Total age increased = (8 * 2) years = 16 years.
Sum of ages of two new men = (21 + 23 + 16) years = 60 years
Average age of two new men = (60/2) years = 30 years.
- 4. The average age of a husband and his wife was 23 years at the time of their marriage. After five years they have a one-year old child. The average age of the family now is :
Options- A. 25
- B. 23
- C. 19
- D. 18 Discuss
Correct Answer: 19
Explanation:
Sum of the present ages of husband, wife and child = (23 * 2 + 5 * 2) + 1 = 57 years.
Required average = (57/3) = 19 years.
- 5. The captain of a cricket team of 11 members is 26 years old and the wicket keeper is 3 years older. If the ages of these two are excluded, the average age of the remaining players is one year less than the average age of the whole team. What is the average age of the team ?
Options- A. 20 years
- B. 21 years
- C. 23 years
- D. 25 years Discuss
Correct Answer: 23 years
Explanation:
Let the average age of the whole team be x years.
11x - (26 + 29) = 9 (x - 1)
=> 11x - 9x = 46
=> 2x = 46
=> x = 23.
So, average age of the team is 23 years.
- 6. The average temperature of the town in the first four days of a month was 58 degrees. The average for the second, third, fourth and fifth days was 60 degrees. If the temperatures of the first and fifth days were in the ratio 7 : 8, then what is the temperature on the fifth day ?
Options- A. 62 degrees
- B. 64 degrees
- C. 65 degrees
- D. 66 degrees Discuss
Correct Answer: 64 degrees
Explanation:
Sum of temperatures on 1st, 2nd, 3rd and 4th days = (58 * 4) = 232 degrees ... (1)
Sum of temperatures on 2nd, 3rd, 4th and 5th days - (60 * 4) = 240 degrees ....(2)
Subtracting (1) From (2), we get :
Temp, on 5th day - Temp on 1st day = 8 degrees.
Let the temperatures on 1st and 5th days be 7x and 8x degrees respectively.
Then, 8x - 7x = 8 or x = 8.
Temperature on the 5th day = 8x = 64 degrees.
- 7. The average monthly salary of the employees of a firm is Rs.60 out of the employees 12 officers get an average of Rs.400 per month and the rest an average of Rs. 56 per month , Find the number of emp
Options- A. 1030
- B. 1032
- C. 1062
- D. 1060 Discuss
Correct Answer: 1032
Explanation:
The actual average salary of 12 officers = 400 therefore Total salary of 12 officers = 400 x 12 = 4800 Average of these 12 officers as a whole =60 Total salary of 12 officers as a whole = 60 x 12 = 720 The total salary of rest = 4800 - 720 = 4080 The difference in average of the rest of officers = 60 - 56 = 4 Rest of the officers = 4080/4=1020 Total number of employees = 1020 + 12 = 1032
- 8. The average salary of all the workers in a workshop is Rs. 8000. The average salary of 7 technicians is Rs. 12000 and the average salary of the rest is Rs. 6000. The total number of workers in the workshop is :
Options- A. 20
- B. 21
- C. 23
- D. 24 Discuss
Correct Answer: 21
Explanation:
Lot the total number of workers be v Then,
8OOOv = (12000 * 7) + 6000 (v - 7) <=> 2000v = 42000 <=> v = 21.
- 9. A team of 8 persons joins in a shooting competition. The best marksman scored 85 points. If he had scored 92 points, the average score for the team would have been 84. The number of points, the team scored was :
Options- A. 665
- B. 657
- C. 658
- D. 678 Discuss
Correct Answer: 665
Explanation:
Let the total score be x.
(x + 92 - 85) / 8 = 84.
So, x + 7 = 672 => x = 665.
- 10. If the arithmetic mean of seventy-five numbers is calculated, it is 35. if each number is increased by 5, then mean of new numbers is :
Options- A. 30
- B. 40
- C. 50
- D. 60 Discuss
Correct Answer: 40
Explanation:
Let the numbers are
By Hypothesis , ......(i)
Mean of new numbers =
By (i)
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