Solved: A manager wishes to check the meanmass of flour put into bags in his factory. He... [IB Mathematics Applications & Interpretation (Math AI)]

Question

HLPaper 1

A manager wishes to check the meanmass of flour put into bags in his factory. He randomlysamples 10 bags and finds the meanmass is 1.478 kg and the standard deviation of thesample is 0.0196 kg.

Find ${s_{n - 1}}$ for this sample.

[2]

Verified

Solution

${s_{n - 1}} = \sqrt {\frac{{10}}{9}} \times 0.0196 = 0.02066 \ldots$ (M1)A1

[2 marks]

Find a 95 % confidence interval for the population mean, giving your answer to4 significant figures.

[2]

Verified

Solution

(1.463, 1.493) (M1)A1

Note: If ${s_n}$ used answer is (1.464, 1.492), award M1A0.

[2 marks]

The bags are labelled as being 1.5 kg mass. Comment on this claim with reference toyour answer in part (b).

[1]

Verified

Solution

95 % of the time these results would be produced by a populationwith mean of less than 1.5 kg, so it is likely the meanmass isless than 1.5 kg R1

[1 mark]

A manager wishes to check the meanmass of flour put into bags in his factory. He randomlysamples 10 bags and finds the meanmass is 1.478 kg and the standard deviation of thesample is 0.0196 kg.

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