Distributions

Question 1

What are the properties of a normal curve?

Answer 1

1. It is bell shaped.
2. It is symmetrical.
3. The mean, median and mode all lie on the line of symmetry.
4. 68% of all the values are within one standard deviation of the mean.
5. 98% of all the values are within two standard deviations of the mean.
6. 99.7% of all the values are within three standard deviations of the mean.

Question 2

What does the width of a curve show?

Answer 2

How spread out the distribution is.

Question 3

What can be used to work out the binomial distribution?

Answer 3

probability of r successes in n trials = nCr x pr x (1-p)n-r

Question 4

What are the properties of the binomial distribution?

Answer 4

1. There is a fixed chance of ‘success’, p
2. There is a fixed chance of ‘failure’, 1-p
3. There is a fixed number of trials, n
4. The trials are independent.

Question 5

When does a trial have a discrete uniform distribution?

Answer 5

When all the outcomes have an equal chance of happening.