Normal Distribution

Question 1

Standardising formula (ND)

Answer 1

Z= X-M/ó

(x- mean / standard deviation)

In formula booklet (swap mean for X and remove root n)

Question 2

When can normal distribution be used/ useful facts about normal distribution curve

Answer 2

-99.7% of data lays within 3 standard Deviations of mean

-Continuous data

-Mean = mode = median

-Distribution is symmetrical

-Points of inflection one SD away from mean

-68% of values lay within one SD of mean (either side)

Question 3

what must the variance and mean be for normal distribution to be valid

Answer 3

np≥5 and n(1−p)≥5

Question 4

what must n and p be for normal distribution to be valid

Answer 4

p close to 0.5
n > 30 (n is large)