Math Problem Statement

A box contains identical balls of which 2 are red, 16 are white and 8 are blue. 3 balls are drawn from the box one after the other without replacement. Find the probability in which A. 3 are red B. The first is blue and the other 2 are red C. Two are white and 1 is blue

Solution

We can approach this problem using the concept of probability and combinations since the balls are drawn without replacement.

Given:

  • 2 red balls
  • 16 white balls
  • 8 blue balls
  • Total balls = 2+16+8=262 + 16 + 8 = 26

Part A: Probability that all 3 balls are red

Since there are only 2 red balls, it is impossible to draw 3 red balls. So, the probability is:

P(3 red)=0P(\text{3 red}) = 0

Part B: Probability that the first ball is blue and the other 2 are red

  • There are 8 blue balls out of 26 total balls, so the probability of drawing the first ball blue is:

P(first is blue)=826P(\text{first is blue}) = \frac{8}{26}

  • After drawing a blue ball, 25 balls remain, and only 2 of them are red. The probability of drawing a red ball next is:

P(second is red)=225P(\text{second is red}) = \frac{2}{25}

  • After drawing one red ball, 24 balls remain, and only 1 of them is red. The probability of drawing the second red ball is:

P(third is red)=124P(\text{third is red}) = \frac{1}{24}

So, the total probability is the product of all these individual probabilities:

P(blue, red, red)=826×225×124P(\text{blue, red, red}) = \frac{8}{26} \times \frac{2}{25} \times \frac{1}{24}

Let’s calculate that:

P(blue, red, red)=8×2×126×25×24=1615600=21950P(\text{blue, red, red}) = \frac{8 \times 2 \times 1}{26 \times 25 \times 24} = \frac{16}{15600} = \frac{2}{1950}

Part C: Probability that 2 balls are white and 1 ball is blue

  • There are 16 white balls out of 26, so the probability of drawing the first white ball is:

P(first white)=1626P(\text{first white}) = \frac{16}{26}

  • After drawing a white ball, 25 balls remain, and 15 of them are white. The probability of drawing the second white ball is:

P(second white)=1525P(\text{second white}) = \frac{15}{25}

  • After drawing 2 white balls, 24 balls remain, and 8 of them are blue. The probability of drawing the blue ball next is:

P(third blue)=824P(\text{third blue}) = \frac{8}{24}

So, the total probability is the product of these individual probabilities:

P(2 white, 1 blue)=1626×1525×824P(\text{2 white, 1 blue}) = \frac{16}{26} \times \frac{15}{25} \times \frac{8}{24}

Let’s calculate that:

P(2 white, 1 blue)=16×15×826×25×24=192015600=465P(\text{2 white, 1 blue}) = \frac{16 \times 15 \times 8}{26 \times 25 \times 24} = \frac{1920}{15600} = \frac{4}{65}

Final Answers:

A. Probability of drawing 3 red balls: 00

B. Probability of drawing the first ball blue and the other two red: 21950\frac{2}{1950}

C. Probability of drawing 2 white balls and 1 blue ball: 465\frac{4}{65}


Do you have any questions or would you like further explanation?

Here are 5 related questions to expand your understanding:

  1. What is the probability of drawing 3 blue balls?
  2. How would the probability change if there were 10 blue balls instead of 8?
  3. What is the probability of drawing 2 red balls and 1 white ball?
  4. How would the results differ if the balls were drawn with replacement?
  5. What is the probability that none of the 3 drawn balls is red?

Tip: When calculating probabilities without replacement, always remember to adjust the total number of available items after each draw!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Probability
Combinatorics

Formulas

P(event) = (favorable outcomes) / (total outcomes)
Combination formula: C(n, r) = n! / [r!(n-r)!]

Theorems

Basic Probability Theorem
Multiplication Rule of Probability

Suitable Grade Level

Grades 9-12