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2.4.5 Normal distribution as a model (A-level only)

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Question 48

A construction supplier provides two types of steel components: girders and industrial bolts. The mass of each component is normally distributed. A girder has a mean mass of 520 kg and a standard deviation of 8 kg. An industrial bolt has a mean mass of 60 kg and a standard deviation of 3 kg.

a.

One girder and 8 industrial bolts are selected at random. Find the probability that the mass of the girder exceeds the combined mass of the 8 industrial bolts.

[4]
b.

A single girder and a single bolt are selected at random. Determine the probability that the mass of the girder is less than 8 times the mass of the single bolt.

[3]

2.4.5 Normal distribution as a model (A-level only) Questions

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