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- Question
- What is the average of first 79 natural numbers?
Options- A. 79
- B. 39
- C. 40
- D. 39.5
- Correct Answer
- 40
ExplanationAverage of first n natural numbers = ( n + 1 ) / 2
= ( 79 + 1 ) / 2
= 40 - 1. The average age of a group of 10 friends is 15 yr. If one friend leaves the group, the average becomes 16 yr. Find the age of the friend who left the group.
Options- A. 5 yr
- B. 4 yr
- C. 6 yr
- D. None of these Discuss
- 2. Find the average of 308, 142, 160, 245 and 25.
Options- A. 176
- B. 178
- C. 175
- D. 174 Discuss
- 3. The average age of A,B,C,D and E is 40 years.The average age of A and B is 35 years and the average age of C and D is 42 years .The age of E is
Options- A. 46
- B. 48
- C. 32
- D. none of these Discuss
- 4. Einstein goes from Ahmedabad To Lucknow at the speed of 40 km/hr and returned at the speed of 60 km/hr .the average speed of Einstein during the whole journey is
Options- A. 48 km/hr
- B. 24 km/hr
- C. 50 km/hr
- D. none of these Discuss
- 5. The average salary of all the 60 employees in an office is Rs. 12,000 per month. if the number of executives is twice the number of non executives employees, then the average salary of all the non executives employees is
Options- A. Rs. 9000
- B. Rs. 8000
- C. Rs. 6000
- D. can't be determined Discuss
- 6. The average of 8 number 21. if each of the number is multiplied by 8,the new set of number is?
Options- A. 8
- B. 21
- C. 29
- D. 168 Discuss
- 7. The average of 50 number is 38 .if two numbers 45 and 55 are discarded , the average of the remaining number is?
Options- A. 36.5
- B. 37.0
- C. 37.5
- D. 37.52 Discuss
- 8. The average score of a cricketer for 10 matches is 43.9 runs. If the average for the first six matches is 53 , the average for the last four matches is?
Options- A. 17.15
- B. 29.75
- C. 30.25
- D. 31 Discuss
- 9. The average height of 30 girls out of a class of 40 is 160 cms and that of the remaining girls is 156 cms. the average height of the whole class is?
Options- A. 11.8
- B. 25
- C. 29.5
- D. 30 Discuss
- 10. If a, b, c, d, e are five consecutive odd number , their average is?
Options- A. 5 (a + 4)
- B. abcd/5
- C. 5 (a + b + c + d + e)
- D. None of these Discuss
Average problems
Search Results
Correct Answer: 6 yr
Explanation:
Age of friend left = Previous average of the age - Number of persons present x Increase in average age
= 15 - ( 10-1 ) x ( 16-15 )
= 15- 9 x 1
= 15 - 9 = 6yr
Correct Answer: 176
Explanation:
sum of observations
= 308 + 142 + 160 245 + 25 = 880
Average = Sum of all observations / Number of observations
=880 / 5
=176
Correct Answer: 46
Explanation:
Age E = ( A + B + C + D + E ) - [ ( A + B ) + ( C + D ) ]
= ( 40 x 5 ) - [ ( 35 x 2 ) + ( 42 x 2 )]
=200 - ( 70 + 84)
= 200 - 154
= 46
Correct Answer: 48 km/hr
Explanation:
Average speed =2 x 40 x 60 / ( 40+ 60)
= 4800 / 100
= 48 km/hr
Correct Answer: can't be determined
Explanation:
No. of executives / No. of non- executives
= 2 / 1
Therefore
Number of executives = 40
and number of non executives employees = 20
now , go through the options
Total salary = 40 x salary of executives + 20 x salary of non-executives
60 x 12000 = 40 x k + 20 x l, here k, l are unknowns
so we con't determine the required average salary
Correct Answer: 168
Explanation:
Average will increase by 8 times.
So average of new members = (21 x 8 ) = 168
Correct Answer: 37.5
Explanation:
Sum of 50 member = (50 x 38 )
= 1900
Sum of 48 member = [1900- (45 + 55 ) ]
= 1800
? Required Average = 1800/48
= 225/6
= 37.5
Correct Answer: 30.25
Explanation:
Let the average for last 4 matches be y.
Sum of score for 10 matches = sum of score for first 6 matches + sum of score of last 4 matches.
So 53 x 6 + 4y = 10 x 43.9
? 4x= 439-318
?4x= 121
? x= 30.25
Correct Answer: 30
Explanation:
Average height of the whole class = sum of height of 40 girls / 40
= (30 x 160 + 10 x 156) / 40
= 159 cms.
Correct Answer: None of these
Explanation:
Since a, b, c, d, e are 5 consecutive numbers so
b = a + 2.
c = a + 4.
d = a + 6.
e = a + 8.
Average = (a + b + c + d + e)/ 5
= [a + (a + 2 ) + (a +4 ) + (a+6 )+ (a+8)] / 5
= (5a+20) / 5
= a + 4
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