S1

Question 0

How do you work out the median for continuous data?

Answer 0

N/2

Use interpolation to find the value of the corresponding term.

Question 1

How do you work out the median for discrete data?

Answer 1

N/2

If n is not a whole number, round the number up and pick the corresponding term.

Question 2

Mean of continuous data?

Answer 2

Sum of fx/ sum of f

Question 3

Variance equation?

Answer 3

(Sum of x/n) squared

Question 4

Standard deviation = ?

Answer 4

Square root of variance.

Question 5

Variance for frequency table or grouped frequency distribution?

Answer 5

((Sum of fx/sum of f)squared)

Question 6

What is the addition rule:

P(A u B) = ?

Answer 6

P(A) + P(B) - P(A n B)

Question 7

Conditional probability:

P(A given B) = ?

Answer 7

P(A n B) / P(B)

Question 8

Multiplication rule:

P(A n B) = ?

Answer 8

P(A|B) x P(B) or the other way round.

Question 9

Independent if?

Answer 9

P(A|B) = P(A) or other way round

P(A n B) = P(A) x P(B)

Question 10

Mutually exclusive rule?

Answer 10

P(A n B) = 0

Question 11

How do you find the mean of a combined set of data?

Answer 11

n1xbar1 + n2xbar2 / (n1 +n2)

Question 12

What information can be used to decide if a distribution is skewed?

Answer 12

Quartiles
Shapes of box plots
Formula:
3(mean-median) / standard deviation (larger value = larger skew)

Question 13

Sxx/Syy = ?

Answer 13

Sum of x^2 - (((sum of x)^2) / n)

Question 14

Sxy = ?

Answer 14

(Sum of x times sum of y) / n

Question 15

r = ?

Answer 15

Sxy / root(SxxSyy)

Question 16

What does r measure?

Answer 16

Linear relationship

Question 17

r=1

Answer 17

Perfect +ve linear correlation

Question 18

r=-1

Answer 18

Perfect -ve linear correlation

Question 19

r=0

Answer 19

No linear correlation

Question 20

What is the line of regression for y on x?

Answer 20

y = a + bx

b = Sxy / Sxx

a = ybar - bxbar

Question 21

What is extrapolation and interpolation?

Answer 21

Interpolation = when you estimate the value of a dependent variable within the range of the data.
Extrapolation = ""outside the range of the data.

Question 22

DRV

What is x and X?

Answer 22

x is a particular value of X.

Question 23

DRV

What does P(X=x) or p(x) refer to?

Answer 23

It refers to the probability that X is equal to a particular value x.

Question 24

DRV

Equation for cumulative frequency distribution?

Answer 24

F(x) = P(X=<x)

Question 25

DRV

What is E(X) equation?

Answer 25

Sum of xP(X=x)

Question 26

DRV

Variance of X = ?

Answer 26

E(X^2) - [E(X)]^2

Question 27

DUD

What are the condition for a discreet uniform distribution?

Answer 27

• A DRV X is defined over a set of n distinct values.

- Each value is equally likely.

Question 28

DUD

E(X) = ?

Answer 28

(n+1) / 2

Question 29

DUD

VAR(X) = ?

Answer 29

(n+1)(n-1) / 12

Question 30

S1 questions:

Answer 30

Paper B

Q 1, 3, 4

Question 31

Area of bar =

Answer 31

k x frequency

Question 32

Frequency density =

Answer 32

Frequency/class width