2010 vcaa exam

[Teen]

Let x be a normally distributed random variable with mean of 5 and variance of 9 and let z be the random variable with the standard normal distribution

Find b such that that pr(x>7)=pr(z,b)
I am getting positive 1.5 but the answer is - 1.5 why ?

Thanks in advance

[BubbleWrapMan]

Typo?

[Reckoner]

Is this 5.b on exam 1?

The question is find b when

So using the formula

Where

We get

However, the the question asks for . The value we got was when .

So through the symmetry of the normal distribution curve,

Here's the graph from the assessment report showing the symmetry of the areas of distribution. 




 

[Teen]

Thanks