Statistics Formula

Question 1

What is the formula to work out the value of k in a histogram?

Answer 1

k = (area of bar)/freq

Question 2

What is the formula for linear interpolation?

Answer 2

linear interpolation = Lower bound of class + (freq into class/freq)Class width

Question 3

What is the formula for frequency density in a histogram?

Answer 3

freq density = freq/class width

Question 4

What is the formula for variance in discrete data?

Answer 4

((∑x^2/n) - (∑x/n)^2))

Question 5

What is the formula for Standard deviation?

Answer 5

√(variance)

Question 6

What is the formula to work out IQR?

Answer 6

Q3 - Q1

Question 7

What is the formula to work out Q1?

Answer 7

n/4

Question 8

What is the formula to work out Q3?

Answer 8

3n/4

Question 9

What is the formula to work out the area of a bar in a histogram?

Answer 9

Area of bar = k x freq

Question 10

What is the formula to work out frequency in a histogram?

Answer 10

Freq = freq density x class width

Question 11

What is the formula in terms of quartiles to show that there is a positive skewness?

Answer 11

Q2 - Q1 < Q3 - Q2

Question 12

What is the formula in terms of quartiles to show that there is a symmetrical skewness?

Answer 12

Q2 - Q1 = Q3 - Q2

Question 13

What is the formula in terms of quartiles to show that there is a negative skewness?

Answer 13

Q2 - Q1 > Q3 - Q2

Question 14

What is the addition rule in probability?

Answer 14

P(AuB) = P(A) + P(B) - P(AnB)

Question 15

What is the multiplication rule in probability?

Answer 15

P(AnB) = P(AIB) x P(B)

or

P(AnB) = P(BIA) x P(A)

Question 16

What is the formula for variance in discrete random variables?

Answer 16

Var = (EX^2) - ((EX)^2))

Question 17

X~N(𝛍,𝛔^2)

In normal distribution what is the formula to transform X into Z? and what does 𝛍 and 𝛔 stand for?

Answer 17

Z = (X - 𝛍)/ 𝛔

𝛍 = mean
𝛔 = standard deviation