model 3 twice, thrice, one third etc. of numbers 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) 12
(b) 18
(c) 9
(d) 6
The correct answers to the above question in:
Answer: (c)
Let the third number be x.
∴ The second number = 2x and the third number = 2 × 2x = 4x
According to the question, ${4x+2x+x}/3$ = 21
⇒ 7x = 21 × 3
⇒ x =${21×3}/7$ = 9
Aliter : Using Rule 15,
From three numbers, first number is 'a’ times of 2nd number, 2nd number is 'b’ times of 3rd number and the average of all three numbers is x, then,
First number = $\text"3ab"/ \text"1+b+ab"$ x ; Second number = $\text"3b"/ \text"1+b+ab"$ x ; Third number = $\text"3b"/ \text"1+b+ab"$ x
a = 2, b = 2, x = 21
First number = $\text"3ab"/ \text"1+b+ab"$x
= ${3×2×2}/{1+2+4}$×21
= $12/7$×21=36
Second number = $\text"3ab"/ \text"1+a+ab"$x = ${3×2}/7$×21 = 18
Third number = $3/ \text"1+a+ab"$x = $3/7$×21 = 9
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Read more twice thrice one third Based Quantitative Aptitude Questions and Answers
Question : 1
Of the three numbers, second is twice the first and also thrice the third. If the average of the three numbers is 44, the largest number is :
a) 36
b) 108
c) 24
d) 72
Answer »Answer: (d)
Let third number be x.
∴ Second number = 3x
and first number = ${3x}/2$
Now, x +3x+${3x}/2$=3×44
⇒ ${8x+3x}/2$=3×44
⇒ 11x = 6 × 44
⇒ x=${6×44}/11 = 24$
∴ The largest number = 3x = 3 × 24 = 72
Question : 2
Of three numbers, the first is 4 times the second and 3 times the third. If the average of all the three numbers is 95, what is the third number ?
a) 130
b) 57
c) 76
d) 60
Answer »Answer: (d)
Let the third number be x,
∴ First number = 3x
∴ Second number = ${3x}/4$
According to the question,
3x + ${3x}/4$ + x = 3 × 95
⇒ ${12x+3x+4x}/4$ = 285
⇒ 19x = 285 × 4
⇒ x = ${285×4}/19$ = 60
Aliter : Using Rule 15,
From three numbers, first number is 'a’ times of 2nd number, 2nd number is 'b’ times of 3rd number and the average of all three numbers is x, then,
First number = $\text"3ab"/ \text"1+b+ab"$ x ; Second number = $\text"3b"/ \text"1+b+ab"$ x ; Third number = $\text"3b"/ \text"1+b+ab"$ x
Here, a = 4, b = $3/4$, x = 95
Third Number = $3/\text"1+b+ab"$ ×x
= $3/{1+{3/4}+4×{3/4}}$×95
= ${3×4}/{4+3+12}$×95 = 60
Question : 3
The average of first three numbers is double of the fourth number. If the average of all the four numbers is 12, find the 4th number.
a) 20
b) $18/7$
c) 16
d) $48/7$
Answer »Answer: (d)
$\text"a+b+c"/3$ =2d
⇒ a + b + c = 6d ...(i)
Also, $\text"a+b+c+d"/4$ = 12
⇒ a + b + c + d = 48
⇒ 6d + d = 48
⇒ 7d = 48
⇒ d = $48/7$
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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