Problem-Solving and Data AnalysisEasy–MediumEstimating defective bulbs in a batch
Problem-Solving and Data Analysis practice question
A random sample of 120 light bulbs is taken from a batch of 6,000, and 3 of the sampled bulbs are found to be defective. Based on the sample, what is the best estimate of the number of defective bulbs in the whole batch?
Answer: 150
3/120 = 2.5%, and 2.5% of 6,000 is 150.
Common wrong answers
- If you answered 3
- 3 is the count in the sample.
- If you answered 50
- 50 divides 6,000 by 120.
- If you answered 1500
- 1500 slips a decimal place.
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