SAT Inference from sample statistics and margin of error Practice Question 10 (Easy)

Question bank / Inference from sample statistics and margin of error

Math · Problem-Solving and Data AnalysisEasy

A city planner selected a random sample of $300$ of the $45{,}000$ households in a city and found that $18\%$ of the sampled households own at least $3$ cars. Based on this sample, which of the following is the best estimate of the number of households in the city that own at least $3$ cars?

$54$

$2{,}500$

$8{,}100$

$36{,}900$

Show answer and explanation

Answer: C

Since the sample was randomly selected, the sample proportion is a reasonable estimate for the city. So about $0.18 \times 45{,}000 = 8{,}100$ households own at least $3$ cars.

Choice A is $18\%$ of the $300$ sampled households, which describes the sample rather than the city.

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