Email
Chat with tutor
logo

Ask Questions, Get Answers

X
 
Questions  >>  CBSE XI  >>  Math  >>  Statistics
Answer
Comment
Share
Q)

The frequency distribution given below : Where A is a positive integer , has a variance of 160. Determine the value of A.

$\begin{array}{1 1}(A)\;9\\(B)\;5\\(C)\;7\\(D)\;15\end{array} $

1 Answer

Comment
A)
Toolbox:
  • Formula used to solve this problem are :
  • Variance $\sigma^2=\large\frac{\sum f_i x_i^2}{\sum f_i} - \bigg(\large\frac{\sum f_ix_i }{\sum f_i } \bigg)^2$
Step 2:
Variance $\sigma^2=\large\frac{\sum f_i x_i^2}{\sum f_i} - \bigg(\large\frac{\sum f_ix_i }{\sum f_i } \bigg)^2$
$160 =\large\frac{92 A^2}{7} -\bigg( \large\frac{22A}{7}\bigg)^2$
$160 = \large\frac{92 A^2}{7} -\large\frac{484 A^2}{49}$
$160= \large\frac{92 \times 7A^2 -484A^2}{49}$
$160 \times 49 =644 A^2 -484 A^2$
$160 \times 49= 160 A^2$
$A^2= \large\frac{160 \times 49}{160}$
$A^2= 49$
$A=\pm 7$
Given A is a positive integer .
The value of A is 7.
Hence C is the correct answer.
Help Clay6 to be free
Clay6 needs your help to survive. We have roughly 7 lakh students visiting us monthly. We want to keep our services free and improve with prompt help and advanced solutions by adding more teachers and infrastructure.

A small donation from you will help us reach that goal faster. Talk to your parents, teachers and school and spread the word about clay6. You can pay online or send a cheque.

Thanks for your support.
Continue
Please choose your payment mode to continue
Home Ask Homework Questions
Your payment for is successful.
Continue
Clay6 tutors use Telegram* chat app to help students with their questions and doubts.
Do you have the Telegram chat app installed?
Already installed Install now
*Telegram is a chat app like WhatsApp / Facebook Messenger / Skype.
...