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4.2.2 Statistical distributions (A-level only)

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Question 52

The duration of a high-precision 3D printing task for a specific mechanical component, SSS, is modelled by a normal distribution with mean 450 seconds and standard deviation 40 seconds.

A technician is scheduled to print a batch of 3 identical components one after another.

Making a reasonable assumption about the printing durations,

a.

find the probability that the total time taken to print the batch of 3 components will exceed 23 minutes.

[4]
b.

State the assumption you have made in part (a).

[1]
c.

A different 3D printer is used for 'Draft' components. The duration, DDD, for this printer to complete one draft component is modelled by a normal distribution with mean 280 seconds and standard deviation 25 seconds.

The technician must decide whether to start a batch of 3 high-precision components or a batch of 5 draft components.

Using a similar assumption to that made in part (a),

find the probability that the total time taken to print the batch of 3 high-precision components is less than the total time taken to print the batch of 5 draft components.

[5]

4.2.2 Statistical distributions (A-level only) Questions

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