QR Review Part 4: Probability

QR Review Probability

Multiple Choice

How many cards are in a standard deck of cards?

• 52

• 48

• 40

• 54

Multiple Choice

How many face cards are in a standard deck of cards?

• 12

• 3

• 16

• 9

Multiple Select

What are the suits in a standard deck of cards?

• hearts

• diamonds

• spades

• clubs

Multiple Choice

What is the probability of drawing a queen from a standard deck of cards?

• 1/13

• 4/52

• 4/48

• 1/12

Simple probability

To determine the probability of something occurring, we write a fraction. It is the number of items we want as the numerator and the total number of items are the denominator.
The probability of drawing a queen from a deck of cards:
4 queens/52 cards
Always reduce! 4/52=1/13

Multiple Choice

Determine the probability of drawing a red 7 from a deck of cards

• 1/26

• 2/52

• 1/52

• 1/25

Multiple Choice

Determine the probability of rolling two dice and getting a sum that is greater than 10.

• 1/12

• 0

• 1/6

• 5/36

Multiple Choice

Determine the probability of flipping a coin and getting TAILs twice in a row.

• 1/4

• 1/2

• 2/4

Simple probability

To determine the probability of two independent events occurring, we determine the probability of each occurring and then multiply them together.
Probability of getting tails: 1 tails/2 sides
1/2 ∙1/2 = 1/4

Multiple Choice

Determine the probability of landing on blue, three times in a row.

• 1/64

• 6/8

• 1/512

• 1/4

Multiple Choice

A bag has 10 marbles. 3 marbles are red, 5 marbles are blue, and 2 marbles are yellow. With replacement, what is the probability of drawing 2 yellow marbles in a row?

• 1/25

• 4/10

• 1/5

• 2/5

Multiple Choice

A bag has 10 marbles. 3 marbles are red, 5 marbles are blue, and 2 marbles are yellow. Without replacement, what is the probability of drawing 2 yellow marbles in a row?

• 1/45

• 4/90

• 1/5

• 3/19

With or Without Replacement

If an event occurs with replacement, simply determine the probability of the event or events occurring.
If an event occurs without replacement, do not forget the total must go down as well.
For the previous problems, drawing 2 yellow marbles without replacement: 2 yellow/10 total ∙1 yellow/9 total
Notice there is now 1 less yellow marble and 1 less total marbles.

Multiple Choice

Determine the probability of drawing a king from a standard deck of cards two times without replacement.

• 1/221

• 1/169

• 2/13

• 7/52

Multiple Choice

Determine the probability of drawing a red card or an ace from a standard deck of cards.

• 7/13

• 15/26

• 1/2

• 4/13

When OR occurs, we add the probability of both events happening.
HOWEVER, if something can occur in both parts, we subtract the items that count in both.
Red or an ace
26/52 red, 4/52 aces, 2/52 red aces

​26/52 + 4/52 - 2/52 = 28/52 = 7/13

Probability with OR

Multiple Choice

A state has four golf teams. Team 1 consists of 12 junior girls, Team 2 consists of 20 junior boys, Team 3 consists of 19 senior girls, and Team 4 consists of 15 senior boys. One of the 66 golfers is chosen at random. What is the probability that the chosen golfer is a girl or belongs to Team 3?

• 40/66
• 31/66
• 27/66
• 35/66

Poll

How comfortable are you with probability?

• 😁

• 😊

• 😕

• 😱