Tag: average

Quizzes (2) Questions (95)

Questions Related to average

Multiple choice maths average arithmetic mean of ap introduction to averages means

If $n^{th}$ term of AP is $4n+1$, then AM of $11^{th}$ to $ 20^{ th}$ terms is 

  1. $61.5$
  2. $63$
  3. $63.5$
  4. $62$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Given: $t _{n}=4n+1$

$A.M.=\cfrac{t _{11}+t _{20}}{2}$
           $=\cfrac{4\times 11+1+4\times 20+1}{2}$
           $=63$

Multiple choice maths average arithmetic mean of ap introduction to averages means

If  $n^{th}$ term of AP is $t _n=4n+1$. Find mean of first $10$ terms.   

  1. $85$
  2. $95$
  3. $23$
  4. $7.5$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Given:
$t _{n}=4n+1$
$\therefore A.M.=\dfrac{\sum _{n=1}^{10}4n+1}{n}$
               $=\dfrac{2n(n+1)+n}{n}$
               $=2n+3$
               $=2\times 10+3$
               $=23$
Multiple choice maths average arithmetic mean of ap introduction to averages means

The  arithmatic mean of $4,6,8$ is

  1. $4$
  2. $6$
  3. $8$
  4. $4.5$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$\Rightarrow$  First adding numbers $4,\, 6$ and $8$ = $4+6+8=18$

$\Rightarrow$   We have number of terms 3
$\Rightarrow$   $Arithemetic\, mean=\dfrac{S}{N}=\dfrac{18}{3}=6$

Multiple choice maths average arithmetic mean of ap introduction to averages means

Find AM of divisors of $100$.

  1. $24$
  2. $25.5$
  3. $24.11$
  4. $21.9$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Divisors of 100 are:

$1, 2, 4, 5, 10, 20, 25, 50, 100$
$\therefore n=9$
$\therefore S=1+2+4+5+10+20+25+50+100=217$
$\therefore A.M.=\dfrac{S}{n}=\dfrac{217}{9}=24.11$

Multiple choice maths average arithmetic mean of ap introduction to averages means

The  Sum of three numbers in AP is $75$, and product of extremities is $609$. The numbrs and AM of 1st two numbers is 

  1. $\{21,25,29\}$, AM $= 23$
  2. $\{13,17,21\}$, AM $= 22$
  3. $\{21,25,29\}$, AM $= 25$
  4. $\{21,22,29\}$, AM $= 23$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let the numbers in A.P.  be (a-d), a, (a+d)

$\therefore (a-d)+a+(a+d)=75$
$\Rightarrow a=25$
Also, $(a-d)(a+d)=609$
$\Rightarrow a^{2}-d^{2}=609$
$\Rightarrow 25^{2}-d^{2}=609$
$\therefore d=\pm4$
The numbers are {21,25,29} or {29,25,21}
According to option, we take {21,25,29}
A.M. of 1st two numbers $=\dfrac{21+25}{2}=23$

Multiple choice maths average arithmetic mean of ap introduction to averages means

If the Arithmetic mean of $8, 6, 4, x, 3, 6, 0$ is $4$; then the value of $x =$

  1. $7$
  2. $6$
  3. $1$
  4. $4$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Arithmetic mean $= \cfrac{\text{sum of all observations}}{\text{no. of observations}}$

$\Rightarrow 4=\cfrac { 8+6+4+x+3+6+0 }{ 7 } \ \Rightarrow 28=27+x\ \Rightarrow x=1$