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