4
QuizMultiple Choice

Unit Test — Unit test

Question 4 • Probability and Statistics with Applications Honors Sem-2-FL-1210300 (2024-2025)

A catering company provides packages for weddings and for showers. The cost per person for small groups is approximately Normally distributed for both weddings and showers. The mean cost for weddings is $82.30 with a standard deviation of $18.20, while the mean cost for showers is $65 with a standard deviation of $17.73. If 9 weddings and 6 showers are randomly selected, what is the probability the mean cost of the weddings is more than the mean cost of the showers?

Answer
A
0.0022
B
0.0335
C
0.9665
D
0.9978

Explanation

Let the difference be the mean wedding cost minus the mean shower cost. Its mean is $82.30 − $65 = $17.30, and its standard error is √(18.20²/9 + 17.73²/6) ≈ $9.44. The probability this difference is greater than zero is Φ(17.30/9.44) ≈ Φ(1.83) = 0.9665, so the correct choice is 0.9665.

AI-written and checked against the verified answer.

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