The Normal Distribution

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Question 68

An electronics engineer measures the resistance, $r$ ohms, of a specific component. The measured resistance, $X$ ohms, is normally distributed with mean $r$ ohms and standard deviation $0.8$ ohms.

Find the probability that $X$ is within $1.0$ ohm of $r$ .

[2]

The same component is measured 25 times and the results are recorded.

Find the probability that the sample mean of these 25 results, $Xˉ\bar{X}$ , is within $0.4$ ohms of $r$ .

[3]

Given that the mean of these 25 measurements is $120.4$ ohms, find a $95%95\%$ confidence interval for $r$ .

[3]

The Normal Distribution Questions

A Level
Maths
The Normal Distribution

A Level
Maths OCR
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