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) 68
(b) 67
(c) 71
(d) 69
The correct answers to the above question in:
Answer: (d)
According to question,
Total marks = 71 × 14 = 994
Correct total marks
= 994 + (56 – 42) + (32 – 74)
= 994 + 14 – 42 = 966
∴ Required average = $966/14$ = 69
Aliter : Using Rule 27,
If the average of n numbers is m later on it was found that two numbers a and b misread as p and q.
The correct average = m +${\text"(a+b-p-q)"}/ \text"n"$.
Here n = 14, m = 71
a = 56, b = 42
p = 32, q = 74
Correct Average
= m +${\text"(a+b-p-q)"}/ \text"n"n$
= 71 +${(56+ 32- 42- 74)}/14$
= 71 -$28/14$
= 71 – 2 = 69
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Read more new average from error Based Quantitative Aptitude Questions and Answers
Question : 1
The mean of 50 numbers is 30. Later it was discovered that two entries were wrongly entered as 82 and 13 instead of 28 and 31. Find the correct mean.
a) 30.66
b) 36.12
c) 38.21
d) 29.28
Answer »Answer: (d)
Required average
= 30+${(28+31-82-13)}/50$
= 30 $(-36/50)$
= 30 – 0.72 = 29.28
Aliter : Using Rule 27,
If the average of n numbers is m later on it was found that two numbers a and b misread as p and q.
The correct average = m +${\text"(a+b-p-q)"}/ \text"n"$.
Here, n = 50, m = 30
a = 28, b = 31
p = 82, q = 13
Correct Average = m + ${\text"(a+b-p-q)"}/ \text"n"n$
= 30 +${(28+31-82-13)}/50$
= 30 +$({59-95}/50)$
= 30 -$36/50$
= 30 – 0.72 = 29.28
Question : 2
The average of 100 items was found to be 30. If at the time of calculation, two items were wrongly taken as 32 and 12 instead of 23 and 11, then the correct average is :
a) 29
b) 29.8
c) 29.5
d) 29.9
Answer »Answer: (d)
Correct sum of 100 items
= 30 × 100 – 32 – 12 + 23 + 11
= 3000 – 44 + 34 = 2990
∴ Required average = 2990 100 = 29.9
Question : 3
The average marks obtained by a student in 6 subjects is 88. On subsequent verification it was found that the marks obtained by him in a subject was wrongly copied as 86 instead of 68. The correct average of the marks obtained by him is
a) 85
b) 87
c) 86
d) 84
Answer »Answer: (a)
Correct sum of marks obtained by the student
= 88 × 6 – 86 + 68
= 528 – 86 + 68 = 510
∴ Correct average = $510/6$ = 85
Aliter : Using Rule 26,
The correct average will be = m +${\text"(a-b)"}/ \text"n"$.
Here, n = 6, m = 88
a = 68, b = 86
Correct mean = m + ${\text"(a - b)"}/\text"n"$
= 88 +${(68 - 86)}/6$
= 88 - $18/6$ = 85
Question : 4
The mean of 100 items was 46. Later on it was discovered that an item 16 was misread as 61 and another item 43 was misread as 34. It was also found that the number of items were 90 and not 100. Then what is the correct mean ?
a) 50.7
b) 50
c) 52.7
d) 52
Answer »Answer: (a)
Required Average
= ${100 × 46 – 61 – 34 + 16 + 43}/90$
= ${4600 – 36}/90$ = $4564/90$ = 50.7
Question : 5
The average weight of the 8 oarsmen in boat is increased by 1$1/2$ kg when one of the crew who weighs 60kg is replaced by a new man. The weight of the new man (in kg) is
a) 68 kg
b) 70 kg
c) 72 kg
d) 71 kg
Answer »Answer: (c)
Weight of the new oarsman = 60 + 8 × $3/2$
= 60 + 12 = 72 kg
Aliter : Using Rule 18,
Here, N = 8, T = 60, t = $3/2$
Weight of new man = T + Nt
= 60 + 8 × $3/2$
= 60 + 12 = 72
Question : 6
A boy found that the average of 20 numbers is 35 when he writes a number '61’ instead of '16’. The correct average of 20 numbers is
a) 37.25
b) 32.75
c) 34.25
d) 34.75
Answer »Answer: (b)
Correct average = 35 - $({61 - 16}/20)$
= 35 – $45/20$
= 35 – 2.25 = 32.75
Aliter : Using Rule 26,
The correct average will be = m +${\text"(a-b)"}/ \text"n"$.
Here, n = 20, m = 35
a = 16, b = 61
Correct mean = m + ${\text"(a - b)"}/\text"n"$
= 35 +${(16 - 61)}/20$
= 35 - $45/20$
= 35 – 2.25 = 32.75
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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