Math Problem Statement

A pair of dice are tossed. What is the probability that doubles are rolled, given that the sum on the two dice is less than 11? (Round your answer to three decimal places.) do this correctly

Solution

To solve this problem, let's break it down into a series of steps.

Step 1: Understand the Problem

We need to find the probability of rolling doubles on a pair of dice, given that the sum of the two dice is less than 11.

Step 2: Identify Possible Outcomes

  1. Total Possible Outcomes for Rolling Two Dice: There are 6×6=366 \times 6 = 36 total outcomes for any roll of two dice since each die has 6 faces.
  2. Condition - Sum Less Than 11: First, let’s find the outcomes where the sum of the dice is less than 11. These sums range from 2 to 10.

Outcomes for Sum Less Than 11

The sums that are possible under this condition are as follows:

  • Sum of 2: (1,1)
  • Sum of 3: (1,2), (2,1)
  • Sum of 4: (1,3), (2,2), (3,1)
  • Sum of 5: (1,4), (2,3), (3,2), (4,1)
  • Sum of 6: (1,5), (2,4), (3,3), (4,2), (5,1)
  • Sum of 7: (1,6), (2,5), (3,4), (4,3), (5,2), (6,1)
  • Sum of 8: (2,6), (3,5), (4,4), (5,3), (6,2)
  • Sum of 9: (3,6), (4,5), (5,4), (6,3)
  • Sum of 10: (4,6), (5,5), (6,4)

Counting these, we have a total of 27 outcomes where the sum is less than 11.

Step 3: Identify Favorable Outcomes (Doubles)

Doubles occur when both dice show the same number. Within the outcomes where the sum is less than 11, the doubles are:

  • Sum of 2: (1,1)
  • Sum of 4: (2,2)
  • Sum of 6: (3,3)
  • Sum of 8: (4,4)
  • Sum of 10: (5,5)

So, there are 5 outcomes where doubles occur under the condition that the sum is less than 11.

Step 4: Calculate the Probability

The probability is the ratio of the number of favorable outcomes to the total number of possible outcomes where the sum is less than 11.

P(doublessum<11)=Number of favorable outcomesTotal outcomes where sum < 11=527P(\text{doubles} \mid \text{sum} < 11) = \frac{\text{Number of favorable outcomes}}{\text{Total outcomes where sum < 11}} = \frac{5}{27}

Step 5: Round the Answer

5270.185\frac{5}{27} \approx 0.185

Thus, the probability that doubles are rolled, given that the sum is less than 11, is approximately 0.185 (rounded to three decimal places).


Would you like more details on any of these steps? Here are some related questions to explore further:

  1. How would the probability change if the sum was less than 10 instead of 11?
  2. What is the probability of rolling a sum greater than or equal to 7 on two dice?
  3. How many total outcomes have a sum of exactly 9 on a pair of dice?
  4. What is the probability of rolling doubles on two dice without any condition?
  5. How does changing to a pair of three-sided dice affect the probability calculations?

Tip: Knowing how to set up a probability space (like the total possible outcomes in dice rolls) is essential for solving conditional probability questions!

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Math Problem Analysis

Mathematical Concepts

Probability
Conditional Probability
Combinatorics

Formulas

P(A | B) = Number of favorable outcomes / Total outcomes meeting condition
Probability of doubles = Number of doubles outcomes / Total outcomes

Theorems

Conditional Probability Theorem

Suitable Grade Level

Grades 9-12