Stats

Question 1

In a normal distribution curve, what is the area under the curve plus and minus one standard deviation from the mean

Answer 1

0.68

Question 2

In a normal distribution curve what is the probability/ area under the curve between plus and minus 2 standard deviations around the mean

Answer 2

0.95

Question 3

In a normal distribution curve, what is the probability/ area under the curve plus and minus 3 standard deviations around the mean

Answer 3

0.997

Question 4

How many standard deviations above and below the mean are all populations classed in, stated by OCR

Answer 4

5 standard deviations

Question 5

When using the inverse normal, what does the calculator always say the area is, left or right of the value

Answer 5

Left

Question 6

What is the general formula to find x, that includes Mu, Z and sigma

Answer 6

x = Mu + Zxsigma

Question 7

In a standardised normal distribution, what is the mean

Answer 7

0

Question 8

In a standardised normal distribution, what is the standard deviation

Answer 8

1

Question 9

What are the 2 rules that apply as to when you can use normal distribution to approximate binomial

Answer 9

• At least 30 trials in the binomial
• The trials multiplied by the probability must be at least 10

Question 10

When approximating the binomial, how do you calculate the mean for the normal distribution

Answer 10

number of trials x probability