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Statistics, EXT1 EQ-Bank 13

The weights of pumpkins on a particular farm are normally distributed with a mean of 13.5 kg and a standard deviation of 3 kg.

A random sample of 15 pumpkins is selected.

Let \(X_1, X_2, X_3, \ldots, X_{15}\) denote the weights of the pumpkins in the sample, and let

\(\overline{X}=\dfrac{X_1+X_2+X_3+\cdots+X_{15}}{15}\).

  1. Find the expected value of \(\overline{X}.\)  (1 mark)

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  2. Find the standard deviation of \(\overline{X}.\)   (1 mark)

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Show Answers Only

a.    \(13.5\)

b.    \(0.775\)

Show Worked Solution

a.    \(E(\overline{X})=\mu=13.5\)

b.    \(\sigma_{\overline{X}}=\dfrac{\sigma}{\sqrt{n}}=\dfrac{3}{\sqrt{15}} \approx 0.775\)

Filed Under: Sampling Distribution of the Mean Tagged With: Band 3, smc-7299-10-Find E(X)/std dev(X), syllabus-2027

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