2012 exam 1 question 8

[roseeblosssom]

I've been having trouble up standing what question 8a in the 2012 exam 1 is asking me! Probability has never exactly been strong for me. If anyone could help that'd be great! XD

[clueless123]

Since it is a normal distribution, you know that the curve is symmetrical.
Pr ( X<106 ) = Pr( X > 94)  *because the deviation from the mean (100 ) is 6 units*
Therefore
Pr(94<x<100)
= Pr(100<x<106)
= Pr(x<106) - Pr(X<100)
= q - 0.5

[Flor]

I think the trick to this question is just recognising they're the same distance from the mean.
Also with these types of questions, it's always good to draw it out to see what you're dealing with.
Anyways, I know that someone else has already answered this question, but I thought I'd just show it to you visually http://oi43.tinypic.com/2v93xxx.jpg

Edit: There is a mistake in the working sorry. 100+6 = 106 haha, not 94 Also, for some reason I've used the letter p in the diagram. It should be Q

[roseeblosssom]

Thank you both, I understand now. Both the explanation and the diagram help me understand. I don't know why but in probability, distributions have been my enemy all year!

Thanks heaps! XD

[Flor]

Thank you both, I understand now. Both the explanation and the diagram help me understand. I don't know why but in probability, distributions have been my enemy all year!

Thanks heaps! XD

No problem! All the best tomorrow