hard z-score question...any ideas? (1 Viewer)

[BlueGirl18]

any help or pointers would be much appreciated! the answer is B, if that helps

 

[CM_Tutor]

Each -score is calculated using the formula where is the student's score, is the class average, and is the class standard deviation.

So, if you substitute Carol's results, you get that .

Doing the same for Zachary and Matilda, you will have three equations with only two unknowns. So, you can find what value of and work for two of them, and then figure out for the third whether the problem is an incorrect or and then find the correction that is needed.

 

[CM_Tutor]

PS: @BlueGirl18, where is this question from?

 

[BlueGirl18]

PS: @BlueGirl18, where is this question from?

ahhh... I see! thanks so much!
its from the Killara maths adv trial. I found it on acehsc. I can send it to you?

 

[CM_Tutor]

ahhh... I see! thanks so much!
its from the Killara maths adv trial. I found it on acehsc. I can send it to you?

Thanks for the offer, but I checked and I do have it - I just didn't recognise it and thought it was an unusual / good question.