A recent survey of 8 comma 000 high school students found that the mean price of a prom dress was 195 point 0 0 dollars with a standard deviation of 12 point 0 0 dollars Alyssa thinks that her school is more fashion conscious and spent more than 195 point 0 0 dollars She collected data from 20 people in her high school and found that the average price spent on a prom dress was 208 point 0 0 dollars Which of the following is the correct z -statistic for this situation?
Use the z-statistic for a sample mean: z = (sample mean − hypothesized mean) ÷ (population standard deviation ÷ √sample size). Substituting the values gives z = (208 − 195) ÷ (12 ÷ √20) ≈ 13 ÷ 2.68 ≈ 4.84. The correct choice is 4.84.
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