StatisticsdrillSample size for a proportion
A statistics problem from Statisticsdrill. Solve it with one answer box, with a fresh sample on every attempt and the worked steps and spreadsheet function in the answer, and it is checked the moment you submit.
The task
A pollster wants to estimate the share of residents who use public transit to within 2% (a margin of 0.02) with 90% confidence. There is no prior estimate, so use the conservative p = 0.5. Use z* = 1.645. How many residents must be surveyed? Give a whole number.
What this problem teaches
The formula: n = z*² p (1 - p) / E².
A hint if you get stuck
n = z*² p(1 - p) / E², rounded up.
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