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) 40.8
(b) 40.2
(c) 48.2
(d) 42.8
The correct answers to the above question in:
Answer: (d)
Total marks obtained by 5 students = 50 × 5 = 250.
Now, in this total marks, 84 is included instead of 48.
∴ Correct total marks = 250 – 84 + 48 = 214
∴ Correct average = $214/5$ = 42.8
Aliter : Using rule 26,
The correct average will be = m +${\text"(a-b)"}/ \text"n"$.
Here, n = 5, m = 50
a = 48, b = 84
Correct Average = m +${\text"(a-b)"}/ \text"n"n$
= 50 +${(48-8)}/5$
= 50 - $36/5$
= 50 – 7.2 = 42.8
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Read more new average from error Based Quantitative Aptitude Questions and Answers
Question : 1
The average weight of 12 crewmen in a boat is increased by $1/3$ kg, when one of the crewmen whose weight is 55kg is replaced by a new man. What is the weight of that new man?
a) 60 kg
b) 58 kg
c) 59 kg
d) 57 kg
Answer »Answer: (c)
Weight of the new man = 55 +$1/3$ ×12 = 59 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 = 12, T = 55, t = $1/3$
Weight of new man = T + Nt
= 55 + 12 ×$1/3$
= 55 + 4 = 59 kg.
Question : 2
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
Question : 3
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 : 4
The average of a collection of 20 measurements was calculated to be 56 cm. But later it was found that a mistake had occurred in one of the measurements which was recorded as 64 cm., but should have been 61 cm. The correct average must be
a) 54.5 cm
b) 53 cm
c) 56.15 cm
d) 55.85 cm
Answer »Answer: (d)
Total length of 20 measurements = 56 × 20 = 1120 cm
Correct length of 20 measurements = 1120 – 64 + 61 = 1117
Correct average = $1117/20$ = 55.85 cm
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 = 20, m = 56
a = 61, b = 64
Correct Average = m +${\text"(a-b)"}/ \text"n"n$
= 56 +$({61-64}/20)$
= 56 -$3/20$
= 56 – 0.15 = 55.85 cm
Question : 5
The average of 10 numbers is calculated as 15. It is discovered later on that while calculating the average one number, namely 36, was wrongly read as 26. The correct average is
a) 18
b) 20
c) 14
d) 16
Answer »Answer: (d)
Correct total of 10 numbers = 15 × 10 – 26 + 36 = 160
∴ Correct average = $160/10$ = 16
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 = 10, m =15
a = 36, b = 26
Correct Average = m + ${\text"(a - b)"}/\text"n"$
= 15 +${(36 – 26)}/10$
= 15 + 1 = 16
Question : 6
A student finds the average of ten 2-digit numbers. While copying numbers, by mistake, he writes one number with its digits interchanged. As a result his answer is 1.8 less than the correct answer. The difference of the digits of the number, in which he made mistake, is
a) 3
b) 2
c) 6
d) 4
Answer »Answer: (b)
Difference in average = 1.8
∴ Difference between the number and the number formed by interchanging the digits
= 1.8 × 10 = 18
(Since 53 – 35 = 18)
∴ Number = 35
∴ Difference of digits = 5 – 3 = 2
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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