Normal Distribution

Question 1

What is Normal Distribution?

Answer 1

Any quantity whose variation depends on random causes is distributed according to the normal norm.
Its importance lies in the fact that a large number of distributions approximate to the normal distribution.

- Uses continuous data.

Question 2

Notation

Answer 2

X ~ (M,Pan)

Question 3

What are the conditions characteristics for normal distribution?

Answer 3

1. Bell-shaped & symmetrical to its mean.
2. A continuous distribution.
3. Mean, Mode & Median are all equal – Because of the symmetrical of its distribution.
4. Total area under the curve is equal to ??
5. Family of curves; Every unique pair of M & S.D defines a different N.D. Thus, the N.D is defined by 2 parameters (M & S.D)
6. It is asymmetrical to the axis (It extends indefinitely in either direction from M. The range from -infinite to +infinite) (The 2 tails of the curve extend indefinitely)

Question 4

What are some examples of using N.D?

Answer 4

• Heights, weights (measures) or time taken.
• Scores in exams.

Question 5

Notation for standard N.D

Answer 5

If there is X, Z = X–M/Pan(S.D)

Question 6

Tips for Normal Distribution.

Answer 6

• When there is Z = do the question directly (Formula, Table)
• When there is X, need to standardise it. (Standardise formula, Formula, Table)
• If given a number Alone = Variance, with a square root = S.D.