Turn on thread page Beta
 You are Here: Home >< Maths

# further maths statistics help watch

1. im really stuck on this question/ dont really know where to start... can someone please explain it to me?

a discrete random variable x has equal expectation and standard deviation. y is a transformation of x such that y=aX-b. prove that it is only possible for the expectation of y to equal the variance of y if b less than or equal to 1/4

thanks
2. From the first bit we know E(X)=rt(E(X^2)-(E(X))^2). Thus, E(X^2)=2E((X))^2. Now if that si for variable X, using the transformation given, what will be E(Y) and E(y^2)?
3. (Original post by Radioactivedecay)
From the first bit we know E(X)=rt(E(X^2)-(E(X))^2). Thus, E(X^2)=2E((X))^2. Now if that si for variable X, using the transformation given, what will be E(Y) and E(y^2)?
oooooh... thanks for the help,much appreciated!

Reply
Submit reply
Turn on thread page Beta

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 12, 2018
Today on TSR

### He lied about his age

Thought he was 19... really he's 14

### University open days

1. University of Bradford
University-wide Postgraduate
Wed, 25 Jul '18
2. University of Buckingham
Psychology Taster Tutorial Undergraduate
Wed, 25 Jul '18
3. Bournemouth University
Clearing Campus Visit Undergraduate
Wed, 1 Aug '18
Poll
Useful resources

## Make your revision easier

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

Can you help? Study help unanswered threads

## Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.