normal distribution question

[Zahta]

Need help with this question please,  question 2. But also question 6b and question 7b and c.  Thanks

[ldee]

Hi, for question 2, i think this is how you do it:

Extended response questions are calculated enabled. So use your calculator to find the inverse normal distribution. Dependent of the calculator you have it will be a little different, but you just input the probability (0.95), mean (10) and standard deviation (2).
Now, it should give the two centre values for which 95% of the data lies.

Take one of these values, lets say you choose the upper value.
It should be 13.92.

13.92 = mean + k
13.92 = 10 + k
k = 3.92

Hope this helps


Anybody feel free to correct me if this method is wrong.