Chapter 4.1 Intro to probability
You guess that there is a 55% chance that you will be assigned homework in your Spanish class on Thursday.
subjective probability
experimental probability
(empirical probability) uses the outcomes obtained by repeatedly performing an experiment to calculate the probability
classical probability
(theoretical probability) is the most precise type of probability and can only be calculated when all possible outcomes in the sample space are down and equally likely to occur
There are 124 identical plastic chips numbered 1 through 124 in a box. What is the probability of reaching into the box and randomly drawing a chip number that is greater than 44?
124-44 = 80 80/124 = .6452
A standard six-sided die is rolled. What is the probability of rolling a number greater than 4?
2/6 = .3333
You decide to record the hair colors of people leaving a lecture at your school. What is the probability that the next person who leaves the lecture will have blonde hair? Blonde Red Brown Black Gray 31 25 18 40 42
31+25+18+40+42= 156 31/156 = .1987 or 31/156
There are 151 identical plastic chips numbered 1 1 through 151 in a box. What is the probability of reaching into the box and randomly drawing a chip number that is smaller than 41 ? Express your answer as a simplified fraction or a decimal rounded to four decimal places.
40/151 = .2649
What is the probability of rolling a sum of 6 on a standard pair of six-sided dice?
6x6 = 36 1+5, 4+5, 3+3, 2+4, 4+2 = 5 ways 5/36 = .1388
not mutually exclusive
can happen at the same time example: choosing a jack; choosing a diamond ( can be a jack thats a diamond)
mutually exclusive
cannot happen at the same time example: turning left and turning right example: tossing a coin - heads and tails
Decide if the following probability is classical, empirical, or subjective. Selecting an 8 from a standard deck of cards
classical probability
What is the probability that a randomly selected person will have a birthday in December? Assume that this person was not born in a leap year. Express your answer as a simplified fraction or a decimal rounded to four decimal places.
december = 31 days 31 / 365 = 0.0849
Decide if the following probability is classical, empirical, or subjective. You calculate that the probability of randomly choosing a student who is left-handed is about 22%
empirical probability
A subset of outcomes of the sample space is called a(n)
event
subjective probability
is an educated guess regarding the chance that an event will occur
Choosing a heart or a club out of a standard deck of cards.
mutually exclusive
Choosing a red card or a spade out of a standard deck of cards.
mutually exclusive
Choosing a heart or a club out of a standard deck of cards.
not mutually exclusive