Math Problem Statement

A box contains 6 black balls and 4 green balls. Three balls were drawn in successive with replacement. What is the probability of getting three the same color?

Solution

To find the probability of drawing three balls of the same color with replacement, we need to consider the two possible outcomes: drawing three black balls or drawing three green balls.

Step 1: Find the probability of drawing a black ball.

Since there are 6 black balls out of a total of 10 balls (6 black + 4 green), the probability of drawing a black ball on any draw is: P(Black)=610=0.6P(\text{Black}) = \frac{6}{10} = 0.6

Step 2: Find the probability of drawing three black balls.

Since the draws are with replacement, the probability of drawing three black balls is: P(Three Black)=P(Black)×P(Black)×P(Black)=0.6×0.6×0.6=0.216P(\text{Three Black}) = P(\text{Black}) \times P(\text{Black}) \times P(\text{Black}) = 0.6 \times 0.6 \times 0.6 = 0.216

Step 3: Find the probability of drawing a green ball.

Similarly, the probability of drawing a green ball is: P(Green)=410=0.4P(\text{Green}) = \frac{4}{10} = 0.4

Step 4: Find the probability of drawing three green balls.

The probability of drawing three green balls is: P(Three Green)=P(Green)×P(Green)×P(Green)=0.4×0.4×0.4=0.064P(\text{Three Green}) = P(\text{Green}) \times P(\text{Green}) \times P(\text{Green}) = 0.4 \times 0.4 \times 0.4 = 0.064

Step 5: Find the total probability of drawing three balls of the same color.

Since the events of drawing three black balls and three green balls are mutually exclusive, we add the probabilities: P(Three Same Color)=P(Three Black)+P(Three Green)=0.216+0.064=0.28P(\text{Three Same Color}) = P(\text{Three Black}) + P(\text{Three Green}) = 0.216 + 0.064 = 0.28

Thus, the probability of drawing three balls of the same color is 0.28 or 28%.


Would you like more details or further explanation?

Here are 5 related questions for further practice:

  1. What is the probability of getting exactly two black balls and one green ball?
  2. What is the probability of getting no black balls?
  3. How does the probability change if the draws are without replacement?
  4. What is the expected number of black balls in three draws?
  5. What is the probability of getting at least one green ball in three draws?

Tip: When dealing with "with replacement" problems, each draw is independent, meaning the probability of each event does not change after each draw.

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Math Problem Analysis

Mathematical Concepts

Probability
Independent Events
Multiplication Rule of Probability

Formulas

P(Black) = 6/10
P(Green) = 4/10
P(Three Black) = P(Black) × P(Black) × P(Black)
P(Three Green) = P(Green) × P(Green) × P(Green)
P(Three Same Color) = P(Three Black) + P(Three Green)

Theorems

Multiplication rule of independent events

Suitable Grade Level

Grades 8-10