Simple Probability Review

Comparing Probability

100

Which probability is greater?

1/4 or 2/5

1/4

200

Which probability is smaller?

.45 or 2/3

.45

300

Which is least likely to happen (smaller probability)?Flipping a heads on a coin or rolling a number less than 3 on a six-sided die

rolling a number less than 3, 1/3

400

Which is more likely to happen (greater probability)?

Having your birthday be in the fall (September-October) or rolling an even number on a six-sided die

rolling an even number, 1/2

500

Which of the following could not be a probability?

0

1/2

3/2

1

3/2, probability goes from 0 to 1

Theoretical Probability

100

What is the theoretical probability of rolling a 4 on a six-sided die?

1/6

200

What is the theoretical probability of rolling an odd number on a six-sided die?

1/2

300

What is the theoretical probability of a classmate's birthday being in March?

1/12

400

What is the theoretical probability of drawing a Queen from a deck of 52 cards?

4/52 = 1/13

500

What is the theoretical probability of drawing a card that is less than 5, out of a deck of 52 cards?

16/52 = 4/13

Experimental Probability

100

What is the definition of experimental probability?

(frequency of an outcome)/(total number of outcomes)

200

What is the experimental probability of flipping heads if in an experiment a coin was flipped 20 times and came up tails 11 times?

9/20

300

What is the experimental probability of rolling an odd number if in an experiment a six sided die was rolled 36 times and the results were:

(1): 4 times      (3): 3 times      (5): 9 times

(2): 7 times      (4): 6 times      (6): 7 times

(4+3+9)/36 = 16/36 = 4/9

400

You plant 30 daffodil seeds and 5 of them sprout. Use experimental probability to predict how many will sprout if you plant 54 seeds?

5/30 = 1/6 and 6*9=54

so 9/54 seeds will sprout

500

If a car factory checks 360 cars and 8 of them have defects, how many will have defects out of 1260?

8/360 = 1/45 and 45*28=1260

so 28/1260 will have defects.

Compound Probability

100

When we find compound probability, the probability of one event occurring and then another, what operation do we use between the two probabilities?

multiplication

200

What is the difference between an independent and dependent events?

If events are dependent the first outcome affects the second outcome.

300

What is the probability of rolling a 3 and then an even number on a six sided die?

1/6 * 3/6 = 3/12 = 1/4

400

In a bag are 3 Snickers, 5 Reeses and 7 Milky Way. What is the probability of grabbing a Snickers, eating it, then grabbing a Milky Way?

3/15 * 7/14 = 21/210 = 1/10

500

There are three doors, behind which one is a prize. What is the probability of selecting one door, and then changing your pick to another door? 

1/3 * 1/2 = 1/6

(Look up the Monty Hall Door problem in your spare time.)

Sample Spaces

100

How many total outcomes are there when you roll a six-sided die?

6

200

How many suits are there in a deck of 52 cards?

4

300

How many cards are in each suit in a deck of 52 cards?

13

400

How many total outcomes will there be if a coin is flipped two times in a row?

4

500

How many total outcomes will there be if two dice are rolled?

36