model 5 find new average from error Section-Wise Topic Notes With Detailed Explanation And Example Questions
MOST IMPORTANT quantitative aptitude - 9 EXERCISES
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Basic Average Questions Practice Test, Shortcuts, Tricks, PDF »
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New Average Aptitude MCQ Average of Consecutive Numbers »
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Top 99+ Average Aptitude: Twice, One Third of Numbers MCQ »
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New +99 Average Aptitude MCQ Find nth Average of Numbers »
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99+ Average Aptitude Find New Average from Error MCQ Test »
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Top 99+ Aptitude MCQ Test on Average With Excluded Number »
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Top 99+ Aptitude Average on Ages & Weights MCQ Test Quiz »
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Top Aptitude Average MCQ Find Monthly Income for Average »
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Top 149+ Aptitude Average on Cricket & Exam MCQ Test Quiz »
The following question based on average topic of quantitative aptitude
(a) 96
(b) 92
(c) 97
(d) 93
The correct answers to the above question in:
Answer: (d)
Sum of marks of top 5 students = 40 × 86 – 35 × 85
= 3440 – 2975 = 465
∴ Their average = $465/5$ = 93
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Read more new average from error Based Quantitative Aptitude Questions and Answers
Question : 1
The mean of 50 observations was 36. It was found later that an observation 48 was wrongly taken as 23. The corrected (new) mean is
a) 36.1
b) 35.2
c) 39.1
d) 36.5
Answer »Answer: (d)
The sum of 50 observations = 50 × 36 = 1800
The correct mean
= ${1800 - 23 + 48}/50$
= $1825/50$ = 36.5
Aliter : Using Rule 26,
The correct average will be = m +${\text"(a-b)"}/ \text"n"$.
Here, n = 50, m = 36
a = 48, b = 23
Correct Average = m + ${\text"(a - b)"}/ \text"n"n$
= 36 +${(48 – 23)}/50$
= 36 +$25/50$ = 36.5
Question : 2
The average of 27 numbers is 60. If one number is changed from 28 to 82, the average is
a) 58
b) 56
c) 64
d) 62
Answer »Answer: (d)
Difference of numbers = 82 – 28 = 54
∴ Required average = 60 + $54/27$ = 62
Aliter : Using Rule 26,
If average of n numbers is m later on it was found that a number 'a’ was misread as 'b’.
The correct average will be = m +${\text"(a-b)"}/ \text"n"$.
Here, n = 27, m = 60
b = 28, a = 82
New Average = m + ${\text"(a - b)"}/\text"n"$
= 60 +${(82 - 28)}/27$
= 60 +$54/27$ = 62
Question : 3
The mean of 20 items is 55. If two items 45 and 30 are removed, the new mean of the remaining items is
a) 65.3
b) 65.1
c) 56
d) 56.9
Answer »Answer: (d)
Sum of 18 items
= 55 × 20 – 45 – 30
= 1100 – 75 = 1025
∴ Required average = $1025/18$ = 56.9
Question : 4
Average weight of 25 persons is increased by 1 kg when one man weighing 60 kg is replaced by a new person. Weight of new person is :
a) 61 kg
b) 50 kg
c) 85 kg
d) 86 kg
Answer »Answer: (c)
Total weight increased = 1 × 25 = 25 kg
∴ Weight of new person = 60 +25 = 85 kg
Aliter : Using Rule 18,
If in the group of N persons, a new person comes at the place of a person of 'T’ years, so that average age,
increases by 't’ years
Then, the age of the new person = T + N.t.
Here, N = 25, T = 60 t = 1
Weight of New person = T + Nt
= 60 + 25 × 1 = 85 Kg
Question : 5
The average of 9 integers is found to be 11. But after the calculation, it was detected that, by mistake, the integer 23 was copied as 32, while calculating the average. After the due correction is made, the new average will be
a) 9
b) 10
c) 9.5
d) 10.1
Answer »Answer: (b)
Sum of 9 integers = 9 × 11 = 99.
New average = ${90+ 23- 32}/9$ = $90/9$ =10
Aliter : Using Rule 26,
The correct average will be = m +${\text"(a-b)"}/ \text"n"$.
Here, n = 9, m = 11
a = 23, b = 32
Correct mean = m + ${\text"(a - b)"}/\text"n"$
= 11 +${(23 -32)}/9$
= 11 +${(-9)}/9$
= 11 – 1 = 10
Question : 6
The average marks secured by 36 students was 52. But it was discovered that an item 64 was misread as 46. What is the correct mean of marks ?
a) 53.5
b) 54
c) 52.5
d) 53
Answer »Answer: (c)
Difference of correct and incorrect marks = 64 – 46 = 18
∴ Correct mean = 52 + $18/36$ = 52.5
Aliter : Using Rule 26,
If average of n numbers is m later on it was found that a number 'a’ was misread as 'b’.
The correct average will be = m +${\text"(a-b)"}/ \text"n"$.
Here, n = 36, m = 52
a = 64, b = 46
New mean = m + ${\text"(a - b)"}/\text"n"$
= 52 +${(64 – 46)}/36$
= 52 + $18/36$
= 52 + $1/2$ = 52.5
GET average PRACTICE TEST EXERCISES
model 1 basic average questions
model 2 average of consecutive numbers
model 3 twice, thrice, one third etc. of numbers
model 4 find nth average from 1st & last number
model 5 find new average from error
model 6 find average of excluded number
model 7 average on ages/weight
model 8 find monthly income
model 9 average on cricket/exam
average Shortcuts and Techniques with Examples
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model 1 basic average questions
Defination & Shortcuts … -
model 2 average of consecutive numbers
Defination & Shortcuts … -
model 3 twice, thrice, one third etc. of numbers
Defination & Shortcuts … -
model 4 find nth average from 1st & last number
Defination & Shortcuts … -
model 5 find new average from error
Defination & Shortcuts … -
model 6 find average of excluded number
Defination & Shortcuts … -
model 7 average on ages/weight
Defination & Shortcuts … -
model 8 find monthly income
Defination & Shortcuts … -
model 9 average on cricket/exam
Defination & Shortcuts …
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