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

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Question 46

The mass of thermal paste in 'Grade-A' high-precision dispensers is normally distributed with a mean of 18.4 g and a standard deviation of 0.8 g.

a.

Calculate the probability that a randomly selected Grade-A dispenser contains a mass of paste exceeding 17.0 g.

[2]
b.

A prototype dispenser, 'Model-Z', is currently calibrated to the 92nd92\text{nd}92nd percentile for mass compared to the Grade-A population. Estimate the mass of paste in a Model-Z dispenser.

[2]
c.

The mass of paste in 'Grade-B' dispensers follows a normal distribution with a standard deviation of 1.2 g. Given that 98% of Grade-B dispensers contain more paste than the mean mass of the Grade-A dispensers,

determine the mean mass of paste in a Grade-B dispenser.

[4]

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

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