Average, General Mathematics

Question: The average of first five prime numbers is:
A
4.5

B
5

C
5.6

D
7.5

Note: Average = $((2+3+5+7+11)/5) = 28/5 = 5.6$
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Question: The average of first five multiples of 3 is:
A
3

B
9

C
12

D
15

Note: Average = $((3(1+2+3+4+5))/5)=45/5=9$
1. Report
Question: The average of first $50$ natural numbers is :
A
$12.25$

B
$21.25$

C
$25$

D
$25.5$

Note: Sum of first n natural numbers $= (n(n + 1))/(2n)$ $= (n + 1)/2$ :. Average $= ((50 + 1)/2)$ $= 51/2$ $= 25 .5$
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Question: The mean of $1^2,2^2,3^2,4^2,5^2,6^2,7^2$ is:
A
$40$

B
$20$

C
$30$

D
$10$

Note: $1^2 + 2^2 + 3^2 +....+n^2$ $= (n(n + 1)(2n + 1))/(6)$ $:. 1^2 + 2^2 +3^2 +......+7^2$ $= ((7 xx 8 xx 15)/6)$ $= 140$ . :. Required average $= (140/7)$ $= 20$
1. Report
Question: The average of all odd numbers upto $100$ is:
A
$51$

B
$50$

C
$49.5$

D
$49$

Note: Sum of odd numbers upto $100$ $= 1 + 3 + 5 + 7 +......+ 95 + 97 + 99$ $= (1 + 99) + (3 + 97) + (5 + 95) +...upto$ 25 $pairs.$ = 100 + 100 + 100+....(25 times)= 2500 $:. Average$ = (2500/50)= 50
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Question: If a,b,c,d,e are five consecutive odd numbers ,thier average
A
$5(a + 4)$

B
$(abcde)/5$

C
$5 (a + b + c + d + e)$

D
None of these

Note: ckearly , $b = a + 2,c = a + 4, d = a + 6 and e = a + 8$ . :. Average $= (a + (a + 2) + (a + 4) + (a + 6) + (a + 8))/5$ $= ((5a + 20)/5)$ $= (a + 4)$
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Question: The average of $7$ consecutive numbers is $33$ .The largest of these numbers is :
A
$36$

B
$32$

C
$30$

D
$28$

Note: Let the numbers be $x,x + 2,x + 4 and$ x + 6 $.Then$ (x + x + 2 + x + 4 + x + 6)/4= 27⇒ (4x + 12)/4= 27 ⇒ x + 3= 27⇒ x = 24 $:. Largest number$ = (24 + 6)= 30
1. Report
Question: The average height of $30$ boys out of a class of $50$ ,is $160$ cm.If the average hieght of the remaining boys is $165$ cm, the average height of the whole class (in cm) is :
A
$161$

B
$162$

C
$163$

D
$164$

Note: Required average $= ((30 xx 160 + 20 xx 165)/50)$ $= 162 cm$ .
1. Report
Question: The average of three numbers is $20$ .If two numbers are $16$ and $22$ , the third is :
A
$22$

B
$20$

C
$19$

D
$18$

Note: Total sum of three numbers $= (20 xx 3)$ $= 60$ Third number $= 60 - (16 + 22)$ $= 22$
1. Report
Question: The average of two numbers is M.If one number is N,then the other number is :
A
$2 N$

B
$2 M$

C
$M - N$

D
$2 M - N$

Note: Total sum of two numbers $= 2 M$ . :. Other number $= (2 M - N)$ .
1. Report

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Question: The average of first five prime numbers is:

Question: The average of first five multiples of 3 is:

Question: The average of first $50$ natural numbers is :

Question: The mean of $1^2,2^2,3^2,4^2,5^2,6^2,7^2$ is:

Question: The average of all odd numbers upto $100$ is:

Question: If a,b,c,d,e are five consecutive odd numbers ,thier average

Question: The average of $7$ consecutive numbers is $33$ .The largest of these numbers is :

Question: The average height of $30$ boys out of a class of $50$ ,is $160$ cm.If the average hieght of the remaining boys is $165$ cm, the average height of the whole class (in cm) is :

Question: The average of three numbers is $20$ .If two numbers are $16$ and $22$ , the third is :

Question: The average of two numbers is M.If one number is N,then the other number is :

Question: The average of first five prime numbers is:

Question: The average of first five multiples of 3 is:

Question: The average of first 5050 natural numbers is :

Question: The mean of 12,22,32,42,52,62,721^2,2^2,3^2,4^2,5^2,6^2,7^2 is:

Question: The average of all odd numbers upto 100100is:

Question: If a,b,c,d,e are five consecutive odd numbers ,thier average

Question: The average of 77consecutive numbers is 3333.The largest of these numbers is :

Question: The average height of 3030boys out of a class of 5050,is 160160cm.If the average hieght of the remaining boys is 165165cm, the average height of the whole class (in cm) is :

Question: The average of three numbers is 2020.If two numbers are 1616 and 2222, the third is :

Question: The average of two numbers is M.If one number is N,then the other number is :

Question: The average of first $50$ natural numbers is :

Question: The mean of $1^2,2^2,3^2,4^2,5^2,6^2,7^2$ is:

Question: The average of all odd numbers upto $100$ is:

Question: The average of $7$ consecutive numbers is $33$ .The largest of these numbers is :

Question: The average height of $30$ boys out of a class of $50$ ,is $160$ cm.If the average hieght of the remaining boys is $165$ cm, the average height of the whole class (in cm) is :

Question: The average of three numbers is $20$ .If two numbers are $16$ and $22$ , the third is :