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- Question
- The average marks of 30 students are 45 but after checking there are two mistakes found. After adjustment if a student got 45 more markes and other student got 15 less marks, then What will be the adjusted average?
Options- A. 45
- B. 44
- C. 47
- D. 46
- Correct Answer
- 44
ExplanationTotal number of all students of the class = 30 x 45 = 1350
? New average after adjustment = (1350 - 45 + 15)/30 = 1320/30 = 44 - 1. The average of 50 number is 38. If the two numbers 45 and 55 are not considered, What will be the average of remaining numbers?
Options- A. 36.5
- B. 37
- C. 37.5
- D. 37.52 Discuss
- 2. If the algebraic sum of deviations of 20 observation measured from 23 is 70, mean of these observation would be
Options- A. 24
- B. 25
- C. 26
- D. 27 Discuss
- 3. Columbus started his journey from Lucknow to Kolkata, Which is 200 K.M., at the speed of 40 KM/hr, then he went to Banglore which is 300 Km, at the speed of 20 KM/hr . Further he went to Ahmedabad which is 500 Km, at the speed of 10 Km/hr. The average speed of Columbus is :
Options- A. 14 2/7 KM/hr
- B. 14 5/7 KM/hr
- C. 15.6 KM/hr
- D. none of these Discuss
- 4. The average height of 40 student is 163 cm. On a particular day, three student A, B, C were absent and the average of the remaining 37 student was found to be 162 cm. if A, B have equal height and the height of C be 2 cm less than that of A, find the height of A?
Options- A. 176 cm
- B. 166 cm
- C. 180 cm
- D. 186 cm Discuss
- 5. The average age of a family of 6 member is 22 years . if the age of the youngest member be 7 years , what was the average age of the family at the birth of the youngest member was?
Options- A. 15 years
- B. 17 years
- C. 17.5 years
- D. 18 years Discuss
- 6. The mean marks obtained by seven students group is 226. If the marks obtained by six of them are 340, 180, 260, 56, 275 and 307 respectively. Find the markes obtained by the seventh student.
Options- A. 164
- B. 226
- C. 340
- D. cannot be determined Discuss
- 7. The average age of 4 member of a family is 25 yr. If head of the family is included in this group then average age increase by 20%. Find out the age of the head.
Options- A. 45 yr
- B. 50 yr
- C. 55 yr
- D. 60 yr Discuss
- 8. The average age of a committee of 11 persons increases by 2 yr when 3 men of 32 yr. 34 yr and 33 yr are replaced by 3 woman. What will be the average age of those 3 woman?
Options- A. 40 yr
- B. 411/3 yr
- C. 41 yr
- D. 401/3 yr Discuss
- 9. The average weight of 10 woman is incraesed by 1 kg if 2 woman of 42 kg and 38 kg are replaced by 2 men.Find the average weight of both the men?
Options- A. 46 kg
- B. 45kg
- C. 42 kg
- D. 44 kg Discuss
- 10. The mean weight of 150 students in class is 60 kg. The mean weight of boys is 70 kg and that of girls is 55 kg. What is the number of boys in the class?
Options- A. 50
- B. 60
- C. 75
- D. 100 Discuss
Average problems
Search Results
Correct Answer: 37.5
Explanation:
According to the basic formula of average,
Average(A)= Sum (S) / Number(N)
? 38 = S/50
? S = 38 x 50 = 1900
Sum of remaining number after eliminating 45 and 55
= 1900 - (45 + 55) = 1800
Average of remaining numbers = (Sum of remaining number) / (Remaining number)
= 1800 / ( 50 - 2)
= 1800/48
= 37.5
Correct Answer:
Explanation:
Mean = (sum of observation) / (number of observation)
Sum of observation is given as = 70
Number of observation = 20
? Mean = 70/20 = 3.5
But, here observation starts from= 23.
? Mean = 23 + 3.5 = 26.5
Correct Answer: 14 2/7 KM/hr
Explanation:
Total distance = (200 + 300 + 500) = 1000
Total time = 200/40 + 300/20 + 500/10 = 5 + 15 + 50 = 70 hr
Average speed = Total distance / Total time =1000 / 70 = 14.2857 Km/hr.
Correct Answer: 176 cm
Explanation:
Let the height of A , B, C be y cm, y cm and (y - 2) cm respectively
Then, y + y + (y - 2) = 163 x 40 - 162 x 37
? 3y - 2 = 526
? y = 176 cm
Correct Answer: 18 years
Explanation:
Total present age of the family = 6 x 22
= 132 years
Total age of the family 7 years ago = 132 - 7 x 6
= 90 years
At that time, the number of members was 5
? Average age at time = 90 / 5 years
= 18 years
Correct Answer: 164
Explanation:
Sum of marks of 7 students = Mean x Number of students
= 226 x 7 = 1582
Now, total marks of 6 students = (340 + 180 + 260 + 56 + 275 + 307) = 1418
? Marks obtained by seventh students
= Total marks of seven students - Total marks of the six student
= 1582 - 1418
= 164
Correct Answer: 50 yr
Explanation:
Total age of 4 member = 25 x 4 = 100 yr
Total age of 5 members including the head
= 5 x (25 + 25 x 20/100)
= 5 x 30 = 150 yr
? Age of the head = 150 - 100 = 50 yr
Correct Answer: 401/3 yr
Explanation:
Total age of 3 woman = 2 X 11 + (32 + 33 + 34)
= 22 + 99 = 121 yr.
? Average age of 3 woman = 121/3 = 401/3 yr
Correct Answer: 45kg
Explanation:
Total weight of 2 men
= 1 x 10 + (42 + 38) = 10 + 80 = 90 kg
? Average weight of 2 men = 90/2 = 45 kg
Correct Answer: 50
Explanation:
Given that total number of students = 150 = ( n1+ n2) and
Mean weight of 150 students = 60 kg.
The mean weight of boys a1= 70 kg and
The mean weight of girls a2 = 55 kg
Let n1 and n2 be the number of boys and girl, respectively.
? n1 + n2 = 150 ...(i)
11 n1 + 11 n2 = 1650 ...(ii)
Average weight = (n1 a1 + n2 a2) / (n1 + n2)
? 60 = (70 n1 + 55n2)/150
? 70 n1 + 55n2 = 9000
? 14n1 + 11n2 =1800 ...(iii)
On subtracting Eq. (ii) from Eq. (iii), we get
3n1 = 150 ? n1 = 50
Hence, required number of boys is 50.
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