normal distribution

Question 1

How to spot normal distribution

Answer 1

• bell shaped curve
• most data clustered around the mean
• mean, median and mode all the same

Question 2

Where is the mean and standard deviation shown on the normal distribution and what symbol represents it

Answer 2

mean (µ - where most of the data is)

standard deviation (σ - how spread out it is)

Question 3

% that show standard deviations

Answer 3

68% will be within 1 s.d
95% will be within 2 s.d
99.7% will be within 3 s.d

Question 4

If data is close to the line on a normal distribution plot, what does this say about the data

Answer 4

It says that the data is normally distributed

Question 5

When do we need to find out the z score

Answer 5

if a value doesn’t fit this we need to calculate its z-score and look up the percentage of the population using statistical tables or your stats calculator.

Question 6

How to calculate the z score

Answer 6

1. Work out how many standard deviations this value is away from the mean
2. Look up the z-score
3. times the z score by 100 to get the percentage.
4. The answer is whatever the rest of the percentage is to make it 100%

Question 7

What is a negative skew

Answer 7

The tail is to the left and curve to the right
The median is greater than the mean

Question 8

What is a positive skew

Answer 8

The tail is to the right and curve to the left
The median is less than the mean

Question 9

Linear transformation formula

Answer 9

y=bx+c

For example to calculate fahrenheit(y) data from celsius data(x) it would involve the following transformation:

Fahrenheit(y) = 1.8(b)x + 32(c)

Question 10

What does linear transformation mean

Answer 10

These convert our data from one measurement scale to another