Question

Difficulty: HardSingle Event Probability

A box contains a mixture of red, blue, and green tokens. There are exactly 1616 red tokens in the box. The probability of randomly selecting a red token is 25\frac{2}{5}. If there are 1414 blue tokens in the box, what is the probability of randomly selecting a green token on a single draw?

  1. 14\frac{1}{4}Answer
  2. B
    35\frac{3}{5}
  3. C
    720\frac{7}{20}
  4. D
    13\frac{1}{3}

Answer

The probability of randomly selecting a green token is 14\frac{1}{4}.
To find the probability of drawing a green token, you must first know the total number of tokens. Because the 1616 red tokens make up 25\frac{2}{5} of the total, the total number of tokens is 16÷25=4016 \div \frac{2}{5} = 40. The box contains 1616 red and 1414 blue tokens, accounting for 3030 tokens. This leaves 1010 green tokens (40−3040 - 30). The probability of selecting a green token is the number of green tokens divided by the total number of tokens: 1040\frac{10}{40}, which reduces to 14\frac{1}{4}.

Step-by-Step Solution

1
Determine the total number of tokens in the box.
Total tokens = 4040
Since 1616 red tokens represent a probability of 25\frac{2}{5}, we can find the total by dividing the part by its fraction: 16÷25=16×52=4016 \div \frac{2}{5} = 16 \times \frac{5}{2} = 40.
2
Calculate the number of green tokens.
Green tokens = 1010
Subtract the known red and blue tokens from the total: 40−16 (red)−14 (blue)=10 green tokens40 - 16 \text{ (red)} - 14 \text{ (blue)} = 10 \text{ green tokens}.
3
Calculate the probability of drawing a green token.
Probability = 14\frac{1}{4}
Probability is the number of favorable outcomes divided by total outcomes: 1040\frac{10}{40}, which simplifies to 14\frac{1}{4}.

Key Concept

Single Event Probability and Total Outcomes
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