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) 18
(b) 20
(c) 14
(d) 16
The correct answers to the above question in:
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
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Read more new average from error Based Quantitative Aptitude Questions and Answers
Question : 1
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 : 2
The average of marks in Mathematics for 5 students was found to be 50. Later, it was discovered that in the case of one student the marks 48 were misread as 84. The correct average is :
a) 40.8
b) 40.2
c) 48.2
d) 42.8
Answer »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
Question : 3
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 : 4
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
Question : 5
The average weight of three men A, B and C is 84 kg. D joins them and the average weight of the four becomes 80 kg. If E whose weight is 3 kg more than that of D, replaces A, the average weight of B, C, D and E becomes 79 kg. The weight of A is
a) 70 kg.
b) 65 kg.
c) 80 kg.
d) 75 kg.
Answer »Answer: (d)
Total weight of A, B and C = 84 × 3 = 252 kg.
Again, A + B + C + D = 80 × 4 = 320 kg.
∴ D = (320 – 252) kg. = 68 kg.
E = 68 + 3 = 71 kg.
B + C + D + E = 79 × 4 = 316 kg.
Now, (A + B + C + D) – (B + C + D +E) = (320 – 316) kg.
∴ A – E = 4 kg.
or A = 4 + E = 4 + 71 = 75 kg
Question : 6
The average weight of 15 students in a class increases by 1.5kg when one of the students weighing 40 kg is replaced by a new student. What is the weight (in kg) of the new student ?
a) 56 kg.
b) 64.5 kg.
c) 62.5 kg.
d) 60 kg.
Answer »Answer: (c)
Weight of the new student
= (40 + 15 × 1.5) kg
= (40 + 22.5) kg
= 62.5 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 = 15, T = 40, t = 1.5
Weight of new Person = T + Nt
= 40 + 15 × 1.5
= 40 + 22.5
= 62.5 kg.
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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