Math Problem Statement

Two dice are rolled with numbers 1-6. Find the probability that; (i) the sum is 13 (ii) the product is 6? (iii) the difference is 1 (iv) the pair of prime number (v) the sum is divisible by 3 or 5?

Solution

To solve this, we analyze the given scenarios based on the outcomes of rolling two dice. Each die has 6 faces numbered 1 through 6, and the total number of outcomes when rolling two dice is 6×6=366 \times 6 = 36.

Now let's address each part of the problem.

(i) Probability that the sum is 13

  • The highest possible sum from rolling two dice is 12 (6 + 6).
  • Since 13 is not achievable, the probability of getting a sum of 13 is 0\boxed{0}.

(ii) Probability that the product is 6

We need to identify the pairs of numbers from the two dice whose product equals 6. The pairs are:

  • (1, 6)
  • (2, 3)
  • (3, 2)
  • (6, 1)

These are 4 favorable outcomes out of 36 total outcomes, so the probability is: P(product = 6)=436=19P(\text{product = 6}) = \frac{4}{36} = \frac{1}{9}

(iii) Probability that the difference is 1

We want the difference between the two dice to be 1. The possible pairs are:

  • (2, 1), (3, 2), (4, 3), (5, 4), (6, 5)
  • (1, 2), (2, 3), (3, 4), (4, 5), (5, 6)

There are 10 favorable outcomes, so the probability is: P(difference = 1)=1036=518P(\text{difference = 1}) = \frac{10}{36} = \frac{5}{18}

(iv) Probability of rolling a pair of prime numbers

Prime numbers between 1 and 6 are 2, 3, and 5. We need to find the pairs where both dice show a prime number. The possible pairs are:

  • (2, 2), (2, 3), (2, 5)
  • (3, 2), (3, 3), (3, 5)
  • (5, 2), (5, 3), (5, 5)

There are 9 favorable outcomes, so the probability is: P(pair of prime numbers)=936=14P(\text{pair of prime numbers}) = \frac{9}{36} = \frac{1}{4}

(v) Probability that the sum is divisible by 3 or 5

We need to check for sums that are divisible by either 3 or 5. The sums of two dice can range from 2 to 12.

  • Sums divisible by 3: 3, 6, 9, 12
  • Sums divisible by 5: 5, 10

Now, let's count how many outcomes give these sums:

  • For sum = 3: (1, 2), (2, 1) → 2 outcomes
  • For sum = 6: (1, 5), (2, 4), (3, 3), (4, 2), (5, 1) → 5 outcomes
  • For sum = 9: (3, 6), (4, 5), (5, 4), (6, 3) → 4 outcomes
  • For sum = 12: (6, 6) → 1 outcome
  • For sum = 5: (1, 4), (2, 3), (3, 2), (4, 1) → 4 outcomes
  • For sum = 10: (4, 6), (5, 5), (6, 4) → 3 outcomes

Adding them all together, we get 2+5+4+1+4+3=192 + 5 + 4 + 1 + 4 + 3 = 19 favorable outcomes. Therefore, the probability is: P(sum divisible by 3 or 5)=1936P(\text{sum divisible by 3 or 5}) = \frac{19}{36}

Final Results:

  1. Probability the sum is 13: 0\boxed{0}
  2. Probability the product is 6: 19\boxed{\frac{1}{9}}
  3. Probability the difference is 1: 518\boxed{\frac{5}{18}}
  4. Probability of a pair of prime numbers: 14\boxed{\frac{1}{4}}
  5. Probability the sum is divisible by 3 or 5: 1936\boxed{\frac{19}{36}}

Would you like more details or have any questions?


Here are 5 related questions to think about:

  1. What is the probability of getting an even product from two dice rolls?
  2. What is the probability that the sum of two dice is a prime number?
  3. How would the probabilities change if the dice had numbers 1-8 instead of 1-6?
  4. What is the probability of rolling a double (the same number on both dice)?
  5. How does the probability of rolling an odd sum compare to rolling an even sum?

Tip: Always break down complex probability questions by first identifying all possible outcomes and then counting favorable ones.

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Math Problem Analysis

Mathematical Concepts

Probability
Combinatorics

Formulas

Probability formula: P(Event) = (Number of favorable outcomes) / (Total number of outcomes)

Theorems

Basic probability theory
Prime number identification

Suitable Grade Level

Grades 6-8