Two Way Tables Flashcards

All 5 cards in this deck

What are the steps to list all possible combinations of one item from each of two lists?

e.g. starters Salad (S), Fish (F); mains Pasta (P), Rice (R)

1. Pair the first item of list 1 with every item of list 2: SP, SR
2. Repeat for the next item of list 1: FP, FR
3. Check the count: $2\times2=4$ combinations

What check tells you a completed two-way table is consistent?

The row totals and the column totals both add up to the grand total in the bottom-right corner.

From a completed two-way table, how do you find the probability that a person chosen at random from everyone is a female with short hair?

Number in the 'female, short hair' cell $\div$ grand total.

e.g. $\frac{8}{45}$

True or false? If one of the females is chosen at random from a two-way table, the probability she has short hair is the number of short-haired females divided by the total number of people.

False. Divide by the total number of females, not the grand total.

True or false? When listing all the possible combinations of one starter and one main course, 'Salad and Pasta' and 'Pasta and Salad' count as the same single combination.

True. One item is taken from each list, so the order you write the pair in does not make a new combination.