These are 6 questions and 6 answers.

To find each probability we will use the definition of probability:

Probability = number of positive outcomes / number of total possible outcomes

1) P(Jack or ten)


Answer: 2/13 ≈ 0.12


Justification:

i) Positive outcomes: A standard deck of cards has 4 jacks and 4 tens, then those are 4 + 4 = 8 different positive outcomes.

ii) Possible outcomes: a standard deck of cards has 52 different cards, so, that is a total of 52 different possible outcomes

iii) Probability, P

P = number of positive outcomes / number of total possible outcomes

P = 8 / 52 = 2/13 ≈ 0.15

 2.P(red or black)


Answer: 1

Justification:

i) Positive outcomes

Half of the cards are red and half of the cards are black, so they both add for the total of the cards = 52

ii) Possible outcomes: 52 cards

iii) Probaility, P

P = number of positive outcomes / number of total possible outcomes

P = 52 / 52 = 1

 3.P(queen or club)


Answer: 4/13 ≈ 0.31

Justification:

i) Positive outcomes

There are 4 Queens.

There are 1/4 of 52 clubs = 1/4 × 52 = 13 clubs.

But you cannot add all of them, because one club is the Quenn of Clubs.

Then, the total number of different Queens and clubs is 4 + 13 - 1 = 16

ii) Possible outcomes: 52 different cards

iii) Probaility, P

P = number of positive outcomes / number of total possible outcomes

P = 16 /52 = 4 / 13 ≈ 0.31

 4.P(red or ace)


Answer: 7 / 13 ≈ 0.54

Justification:

i) Positive outcomes

Half of the cards are red: 26

There are 4 aces.

Since 2 aces are red, the number of different red and aces cards is: 26 + 4 - 2 = 28

ii) Possible outcomes: 52 different outcomes

iii) Probaility, P

P = number of positive outcomes / number of total possible outcomes

P = 28 / 52 = 7 / 13 ≈ 0.54

 5.P(diamond or black)


Answer: 1/2 = 0.5

Justification:

i) Positive outcomes

There are 52 / 4 = 13 diamonds

There are 26 black cards.

All the diamonds are black cards.

Then, the number of different diamond or black cards is 13 + 26 - 13 = 26

ii) Possible outcomes: 52 different cards.

iii) Probaility, P

P = number of positive outcomes / number of total possible outcomes

P = 26 / 52 = 1/2 = 0.5

6.P(face card or spade)

Answer: 11/26 ≈ 0.42

Justification:

i) Positive outcomes

Face cards are jacks, queens and kings. That is 3 × 4 = 12 different cards.

The spades are 13 cards.

Since, 3 of the faces are spade cards, the number of different cards of those types are 12 + 13 - 3 = 22

ii) Possible outcomes: 52 different cards

iii) Probaility, P

P = number of positive outcomes / number of total possible outcomes

P = 22 / 52 = 11 / 26 ≈ 0.42

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