What’s the difference?

In certain situations, a selection reduces the number of items that can be selected in the next trial. These trials are dependent trials (since each decision is based on the previous trial) so because the probability of success changes as each trial is made, we need to use a formula that uses combinations.

a is the number of successful outcomes among a total of n possible outcomes. r is the number of trials

rn

xranxa

CCC

xP )(

nraxE )(

There are 18 people in a jury pool, 8 of whom are men. For a civil trial, the jury comprises of 6 people. Calculate the expected number of women on the jury.

r = 6 a = 10 n = 18

Last summer, the Canadian Wildlife Foundation caught 500 elk, tagged them and released them into the wildlife. This summer, they caught 40 elk, 15 of which were tagged. What is the current population of elk?

HomeworkPg 404 # 1,3,4,8,9