AP Statistics 6.1 Introducing Statistics: Why Be Normal?- MCQs - Exam Style Questions
▶️ Answer/Explanation
Detailed solution
1. Find the Z-Score for the \(25^{th}\) Percentile:
We need to find the z-score that corresponds to an area of \(0.25\) to the left on a standard normal curve. Using a calculator or z-table (inverse normal function), this z-score is approximately \(-0.674\).
2. Calculate the Weight (x-value):
Use the formula \(x = \mu + z\sigma\).
\(x = 8.0 + (-0.674)(1.5)\)
\(x = 8.0 – 1.011 = 6.989\)
The baby’s weight is approximately \(6.989\) pounds, which is closest to \(7.00\) pounds.
✅ Answer: (C)