A drink machine dispenses mu = 200 ml with sigma = 15 ml (normally distributed). The probability that a cup contains between 191 and 209 ml, i.e., P(191 < X < 209), is found using z-scores of:

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CSS Statistics QUESTION #2003

Question 1

A drink machine dispenses \(\mu = 200\) ml with \(\sigma = 15\) ml (normally distributed). The probability that a cup contains between 191 and 209 ml, i.e., \(P(191 < X < 209)\), is found using \(z\)-scores of:

\(z = \pm 0.4\)
\(z = \pm 0.6\)✔️
\(z = \pm 0.9\)
\(z = \pm 1.2\)

Correct Answer Explanation

\(z = \dfrac{191 - 200}{15} = -0.6\) and \(z = \dfrac{209 - 200}{15} = +0.6\). So \(P(-0.6 < Z < 0.6) \approx 0.4515\) from standard normal tables. The correct \(z\)-values are \(\pm 0.6\).

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