Average problems
- 1. The average of class in 35 yr. 6 new students with an average age of 33 yr. joined in that class, there by decreasing the average by half year. The original strength of the class was
Options- A. 14
- B. 18
- C. 16
- D. 20 Also asked in: Bank Exams
Correct Answer: 18
Explanation:
Let the number of students in the class = N
According to the question,
(35N + 6 x 33) / (N + 6) = 35 - (1/2)
? 35N + 198 = 34.5 (N + 6)
? 35N +198 = 34.5N + 207
? 0.5N = 207 -198N = 9/0.5 = 18
? N = 18 days
- 2. The average age of 5 member of a family is 25 yr. If the servant of the family is included the average age increased by 40% .What is the age of servant?
Options- A. 85 yr
- B. 90 yr
- C. 73 yr
- D. 55 yr Discuss
Correct Answer: 85 yr
Explanation:
Total age of 5 members = 25 x 5 = 125 yr
Total age of 5 member and the servant
= (25 + 25 x 40/100) x 6
= 35 x 6 = 210 yr
? Age of the servant = 210 - 125 = 85 yr
- 3. The average age of the 30 woman decreases by 3 month if a new person Priyanka is included in place of 25 yr old woman. Calculate the age of Priyanka.
Options- A. 17.5 yr
- B. 20 yr
- C. 30 yr
- D. 22 yr Discuss
Correct Answer: 17.5 yr
Explanation:
Here, average decreases by 3 months of 3/12 yr.
Sum of ages decreased
= 30 x 3/12 = 15/2 = 7.5 yr
? Age of priyanka = (25 - 7.5) = 17.5 yr.
- 4. The mean temperature of Monday to Wednesday was 37°C and of Tuesday to Thursday was 34°C. If the temperature on Thursday was 4/5 that of Monday, the temperature of Thursday was
Options- A. 35.5°C
- B. 34°C
- C. 36.5°C
- D. 36°C Discuss
Correct Answer: 36°C
Explanation:
Temperature of (Mon + Tue + Wed) = 37 x 3 = 11°C
Temperature of (Tue + Wed + Thu) = 34 x 3 = 102°C
Temperature of (Mon - Thu) = 111°C - 102°C = 9°C
Temperature of [Mon - 4/5(Mon] = 9
Temperature of Monday = 9 x 5 = 45°C
? Temperature of Thursday = 45 x 4/5 = 36°C
- 5. The average of 11 numbers is 36. Out of these 11 numbers, the average of 9 numbers is 34. If the ratio of remaining two numbers is 2 : 3, find out the smaller number.
Options- A. 18
- B. 36
- C. 54
- D. 48 Discuss
Correct Answer: 36
Explanation:
Sum of 11 numbers = 36 x 11 = 396
Sum of 9 numbers = 34 x 9 = 306
Sum of remaining two numbers =396 - 306 = 90
? The smaller number = (2 x 90)/(2 + 3) = 180/5 = 36
- 6. The average of 5 consecutive old positive integers is 9. The least one amongt them is
Options- A. 5
- B. 3
- C. 1
- D. 7 Discuss
Correct Answer: 5
Explanation:
Let the 5 consecutive positive integers be x + 1, x + 3, x + 5, x + 7, x + 9
Average = (Sum of all terms) / (Number of terms)
⇒ 9 = [(x + 1) + (x + 3) + (x + 5) + (x + 7) + (x + 9)]/5
⇒ 9 = (5x +25)/5
⇒ 45 = 5x + 25
⇒ 5x = 45 - 25
∴ 5x = 20 ⇒ x = 4
The least one is x + 1 = 4 + 1 = 5
- 7. The average of the test scores of a class of 'm' students is 70 and that of 'n' students is 91. When the scores of both the classes are combined, the average is 80. What is n/m?
Options- A. 11/10
- B. 13/10
- C. 10/13
- D. 10/11 Discuss
Correct Answer: 10/11
Explanation:
According to the question,
70m + 91n = 80 (m + n)
⇒ 70m + 91n = 80m + 80n
⇒ 10m = 11n
⇒ n/m = 10/11
- 8. If 47a + 47b = 5452, what is the average of a and b?
Options- A. 116
- B. 23.5
- C. 96
- D. 58 Discuss
Correct Answer: 58
Explanation:
47(a + b) = 5452
? a + b = 5452/47 = 116
? Average value = (a + b)/2
= 116/2
= 58
- 9. The average salary per head of all workers of an institution is ? 60. The average salary per head of 12 officers is ? 400. The average salary per head of the rest is ? 56. Then, the total number of workers in the institutions?
Options- A. 1030
- B. 1032
- C. 1062
- D. 1060 Discuss
Correct Answer: 1032
Explanation:
Let The total number of workers = N
According To the question,
60N = 12 x 400 + 56 (N - 12)
? 60N - 56N = 4800 - 672
? 4N = 4128
? N = 1032
- 10. Roshan bought 5 pants at ?25 each, 10 shirts at ? 50 each and 15 ties at ? 35 each. Find the average price of all the articles.
Options- A. ? 38.33
- B. ? 45
- C. ? 60
- D. ? 45.33 Discuss
Correct Answer: ? 38.33
Explanation:
Here, n1 = 5, n2 = 10, n3 = 15, a1 = 25, a2 = 50, a3 = 35
According to the formula,
Average price = (n1a1 + n2a2 + n3a3) / (n1 + n2 + n3)
= (5 x 25 + 10 x 50 + 15 x 35) / (5 + 10 + 15)
= (25 + 100 + 105) / (1 + 2 + 3)
= 230/6
= ? 38.33
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