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Bill and Ben each have three cards, numbered 1, 2 and 3.
123
Bill's cards
They each take one of their own cards.
123
Ben's cards
Then they multiply together the two numbers on the cards.
a) What is the probability that their answer is an even number?
b) What is the probability that their answer is a number greater than 5?



Answer :

Sure, let's solve this step-by-step.

### Problem Setup:

Bill and Ben each have three cards numbered 1, 2, and 3. They each pick one card and then multiply the numbers on their chosen cards.

### Part (a): Probability that the product is an even number

Step-by-Step Solution:

1. List all possible outcomes:
Let's list all the combinations of the cards they can pick:
- Bill picks 1, Ben picks 1: [tex]\(1 \times 1 = 1\)[/tex]
- Bill picks 1, Ben picks 2: [tex]\(1 \times 2 = 2\)[/tex]
- Bill picks 1, Ben picks 3: [tex]\(1 \times 3 = 3\)[/tex]
- Bill picks 2, Ben picks 1: [tex]\(2 \times 1 = 2\)[/tex]
- Bill picks 2, Ben picks 2: [tex]\(2 \times 2 = 4\)[/tex]
- Bill picks 2, Ben picks 3: [tex]\(2 \times 3 = 6\)[/tex]
- Bill picks 3, Ben picks 1: [tex]\(3 \times 1 = 3\)[/tex]
- Bill picks 3, Ben picks 2: [tex]\(3 \times 2 = 6\)[/tex]
- Bill picks 3, Ben picks 3: [tex]\(3 \times 3 = 9\)[/tex]

2. Count the number of possible outcomes:
There are [tex]\(3 \times 3 = 9\)[/tex] possible outcomes since each player has three choices independently.

3. Identify the even outcomes:
- [tex]\(1 \times 2 = 2\)[/tex]
- [tex]\(2 \times 1 = 2\)[/tex]
- [tex]\(2 \times 2 = 4\)[/tex]
- [tex]\(2 \times 3 = 6\)[/tex]
- [tex]\(3 \times 2 = 6\)[/tex]

These are 5 outcomes where the product is even.

4. Calculate the probability:
[tex]\[ P(\text{even product}) = \frac{\text{number of even outcomes}}{\text{total number of outcomes}} = \frac{5}{9} \][/tex]

So, the probability that the product is an even number is [tex]\(\frac{5}{9}\)[/tex].

### Part (b): Probability that the product is greater than 5

Step-by-Step Solution:

1. List all possible outcomes (reused from Part (a)):
- Bill picks 1, Ben picks 1: [tex]\(1 \times 1 = 1\)[/tex]
- Bill picks 1, Ben picks 2: [tex]\(1 \times 2 = 2\)[/tex]
- Bill picks 1, Ben picks 3: [tex]\(1 \times 3 = 3\)[/tex]
- Bill picks 2, Ben picks 1: [tex]\(2 \times 1 = 2\)[/tex]
- Bill picks 2, Ben picks 2: [tex]\(2 \times 2 = 4\)[/tex]
- Bill picks 2, Ben picks 3: [tex]\(2 \times 3 = 6\)[/tex]
- Bill picks 3, Ben picks 1: [tex]\(3 \times 1 = 3\)[/tex]
- Bill picks 3, Ben picks 2: [tex]\(3 \times 2 = 6\)[/tex]
- Bill picks 3, Ben picks 3: [tex]\(3 \times 3 = 9\)[/tex]

2. Identify the outcomes greater than 5:
- [tex]\(2 \times 3 = 6\)[/tex]
- [tex]\(3 \times 2 = 6\)[/tex]
- [tex]\(3 \times 3 = 9\)[/tex]

These are 3 outcomes where the product is greater than 5.

3. Calculate the probability:
[tex]\[ P(\text{product > 5}) = \frac{\text{number of outcomes > 5}}{\text{total number of outcomes}} = \frac{3}{9} = \frac{1}{3} \][/tex]

So, the probability that the product is greater than 5 is [tex]\(\frac{1}{3}\)[/tex].

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