model 1 basic average questions 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) 17
(b) 31
(c) 7
(d) 3
The correct answers to the above question in:
Answer: (c)
Using Rule 1,
Average of two or more numbers/quantities is called the mean of these numbers, which is given by
$\text"Average(A)" = \text"Sumof observation / quantities"/\text"No of observation / quantities"$
∴ S = A × n
Mean = ${3 +11+ 9+7+15+ 13+ 8 +19 +17 +21 +14+x}/12$
According to question,
${137+x}/12$ = 12
∴ 137 + x = 144
∴ x = 144 – 137 = 7
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Read more simple average Based Quantitative Aptitude Questions and Answers
Question : 1
The average of 100 observations was calculated as 35. It was found later, that one of the observations was misread as 83 instead of 53. The correct average is :
a) 35.7
b) 36.7
c) 34.7
d) 32.7
Answer »Answer: (c)
Difference = 83 – 53 = 30
Incorrect observation > Correct observation
∴ Required average
= 35 - $30/100$ = 35 – 0.3 = 34.7
Question : 2
Three Science classes A, B and C take a Life Science test. The average score of class A is 83. The average score of class B is 76. The average score of class C is 85. The average score of class A and B is 79 and average score of class B and C is 81. Then the average score of classes A, B and C is
a) 80.5
b) 80
c) 81
d) 81.5
Answer »Answer: (d)
Using Rule 10,
If the average of '$n_1$' numbers is $a_1$ and the average of '$n_2$' numbers is $a_2$, then average of total numbers $n_1$ and $n_2$ is
$Average = {n_1a_1 + n_2a_2}/{n_1 + n_2}$
Students in class A ⇒ x
Students in class B ⇒ y
Students in class C ⇒ z
For classes A and B,
${83x + 76y}/{x+y}$ = 79
⇒ 83x + 76y = 79x + 79y
⇒ 83x – 79x = 79y – 76y
⇒ 4x = 3y
For classes B and C
${76y+85z}/{y+z}$= 81
⇒ 76y + 85z = 81y + 81z
⇒ 5y = 4z
∴ 20x = 15y = 12z
⇒ ${20x}/60$ = ${15y}/60$ = ${12z}/60$
⇒ $x/3$ = $y/4$ = $z/5$
∴ Required average
${83×3+76×4+85×5}/{3+4+5}$
${249+304+425}/12$ = $978/12$
= 81.5
Question : 3
Out of 20 boys, 6 are each of 1 m 15 cm height, 8 are of 1 m 10 cm and rest of 1 m 12 cm. The average height of all of them is
a) 1 m 21 cm
b) 1 m 12 cm
c) 1 m 21.1 cm
d) 1 m 12.1 cm
Answer »Answer: (d)
Using Rule 2,
If the given observations (x) are occuring with certain frequency (A) then,
$Average = {A_1x_1+A_2x_2+...............+A_nx_n}/{x_1+x_2+......+x_n}$
where, $A_1, A_2, A_3, .......... A_n$ are frequencies
Average height
= ${6×1.15+8×1.1+6×1.12}/20$
= ${6.9+8.8+6.72}/20$ = ${22.42}/20$
= 1 metre 12.1 cm
Question : 4
The average of 30 numbers is 15. The average of the first 18 numbers is 10 and that of the next 11 numbers is 20. The last number is
a) 60
b) 50
c) 52
d) 56
Answer »Answer: (b)
Let the last number be x.
According to the question,
18 × 10 + 11 × 20 + x = 30 × 15
⇒ 180 + 220 + x = 450
⇒ 400 +x = 450
⇒ x = 450 – 400 = 50
Question : 5
The average of marks obtained by 100 candidates in a certain examination is 30. If the average marks of passed candidates is 35 and that of the failed candidates is 10, what is the number of candidates who passed the examination?
a) 80
b) 90
c) 70
d) 60
Answer »Answer: (a)
Number of successful students in the exam = x
∴ Number of unsuccessful students = 100 – x
According to the question,
30 = ${35x+10(100-x)}/100$
⇒ 3000 = 35x + 1000 – 10x
⇒ 3000 = 25x + 1000
⇒ 25x = 3000 – 1000 = 2000
⇒ x = $2000/25$ = 80
Question : 6
The average of 20 numbers is 15 and the average of first five is 12. The average of the rest is
a) 14
b) 13
c) 15
d) 16
Answer »Answer: (d)
If the average of remaining numbers be x, then
20 × 15 = 5 × 12 + 15x
⇒ 300 = 60 + 15x
⇒ 15x = 300 – 60 = 240
⇒ x = $240/15$ = 16
Aliter : Using Rule 13,
Here, m = 20, x = 15
n = 5, y = 12
Average of remaining Numbers = $({mx-ny}/{m-n})$
= $({20×15-5×12}/{20-5})$
= $({300-60}/15)$ = $240/15$ = 16
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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