Marshall spins a prize wheel with 4 segments of equal size, one of which is labeled "winner." Let $X =$ the number of spins until Marshall wins a prize.



Check the conditions to determine if this is a geometric setting.

  1. Are the outcomes binary? [ ]

Success/Failure: [ ]

  1. Are the trials independent? [ ]
  2. Are we counting the number of trials to obtain the first success? [ ]
  3. Is the probability of success the same for each trial? [ ]

Verified Answer :

  • The scenario is a geometric setting because it meets all four required conditions.
  • Binary outcomes exist: landing on a "winner" segment is a success and landing on any other is a failure.
  • Trials are independent: each spin of the wheel is independent of the previous ones.
  • Trials are counted until the first success: the random variable \(X\) measures the spins until the "winner" is achieved.
  • Probability is constant: the probability of success remains \(\frac{1}{4}\) for every trial.
  • Final determination: \(\boxed{\text{Yes}}\)

Explanation

  1. Analysis of the Geometric Setting Criteria

To determine if a scenario is a geometric setting, we must verify if it satisfies four specific criteria related to a sequence of Bernoulli trials. A geometric setting arises when we perform independent trials until the first success occurs, with each trial having the same probability of success. In this case, Marshall spins a prize wheel with 4 equal segments, where landing on the "winner" segment constitutes a success. Let \(X\) be the number of spins until he lands on the "winner" segment.

  1. Evaluating the Four Geometric Conditions

We evaluate each condition for our scenario:

  1. Binary Outcomes: Each spin results in either a "winner" (Success) or "not a winner" (Failure). Since there are only these two possible categories, the outcomes are binary.
  2. Independent Trials: The outcome of any single spin of the prize wheel does not influence the outcome of any subsequent spin. Each spin is physically independent of the others.
  3. Counting Trials until Success: The random variable \(X\) is explicitly defined as the number of trials needed to achieve the first success. This is the definition of a geometric random variable.
  4. Constant Probability of Success: The wheel has 4 segments of equal size, and only one is labeled "winner." Therefore, the probability of success is always \(p = \frac{1}{4}\) for every spin. Since this value does not change, the probability of success is constant.
  1. Conclusion on the Geometric Setting

Because the scenario satisfies all four conditions—binary outcomes, independence, counting trials until success, and a constant probability of success—we conclude that this is indeed a geometric setting. Each spin is a Bernoulli trial, and we are counting the trials until the first success.

Examples

Geometric distributions are widely used in quality control and reliability engineering. For example, if a machine produces a defect with probability \(p\), the number of items produced until the first defective item appears follows a geometric distribution. This helps engineers estimate how many products can be manufactured before a maintenance check is required. If the probability of a defect is \(p = 0.05\), the expected number of items produced before the first defect is \(E[X] = \frac{1}{p} = \frac{1}{0.05} = 20\).