Algebra 1- Joint and marginal frequency tables

Relative Frequency

How often something happens divided by all outcomes.

Example: Your team has won 9 games from a total of 12 games played:

• the Frequency of winning is 9
• the Relative Frequency of winning is 9/12 = 75%

All the Relative Frequencies add up to 1 (except for any rounding error).

Example: Travel Survey

92 people were asked how they got to work:

• 35 used a car
• 42 took public transport
• 8 rode a bicycle
• 7 walked

The Relative Frequencies (to 2 decimal places) are:

• Car: 35/92 = 0.38
• Public Transport: 42/92 = 0.46
• Bicycle: 8/92 = 0.09
• Walking: 7/92 = 0.08

0.38+0.46+0.09+0.08 = 1.01

(It would be exactly 1 if we had used perfect accuracy)

Source:https://www.mathsisfun.com/data/relative-frequency.html

Assignment

 Each student in a random sample of students at a local high school was categorized according to gender (male or female) and whether they supported a proposal to increase the length of the school day by 30 minutes (oppose, support, no opinion). The following table summarizes the data for this sample.

		Opinion on Proposal to Increase Length of School Day
		Oppose	Support	No Opinion	Total
Gender	Male	50	40	20	110
	Female	40	40	10	90
	Total	90	80	30	200

a.             What proportion of the students in this sample are male?
 

b.             What proportion of the students in this sample support the proposal?
 

c.              What proportion of the males in this sample support the proposal?
 

d. What proportion of the students in this sample who support this proposal are female?