Normal Distribution 7 • Missing Mean and/or Standard Deviation • Stats2 Ex3E • 🎲

Edexcel Applied Year 2 - Statistics

Thurs 5/3/20

[notsezz]

great teaching bro i understood the whole topic after 2 years

[Blessing_]

For the question in the end for d, is the answer "the standard deviation decreased which tells us the supervisors claim is correct"

[Dazzletoad]

Nice video, but at the end I don't know what's going on with the calculator.

Re: the P(Y<150) question, you end up with two things, with sigma ommitted because its a x1 multiplier. They are:

1. 160 = m + 2.3263
2. 152 = m - 1.2816

When I saw this simultaneous, the calculator seems unnecessary, aside expedition. You cannot subtract, because you will lose the variable which is the thing you want, so you add them and divide the whole lot by 2.

That will give a single mean value, which comes out for you through the calculator as:

154.8417639

When I did the same thing with the calculator and my method, [ 160+152 = (2)m + 2.3263 - 1.2816 /all divided by 2/) using the same rounded values, I'm getting:

155.4777 = m (to 4 dp)

Considering we both used the same rounded values, set the simultaneous equation up as above, and both used a calculator, can you please tell me where I've gone wrong, because I'm confident you are correct.

Kind thanks.

[casparclark]

This is so useful. quick question, how do you know when to use left or right tails on the calculator?

[rubiksworld]

Hi sir, in an earlier video you said z values were not needed. I was just wondering how you’d do these questions without standardising the values please?

[jingrosie]

How would you know when to take the positive or negative values of an area

[kavinaa]

Hello, i just wanted to ask isnt -4/-0.7998=5.001

[chrishill]

Hi sir, do you have the answers for the exam question you showed at the end?