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2.4 Statistical Distributions

2.4 Statistical Distributions

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Question 240

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]
Markscheme

2.4 Statistical Distributions Questions

  1. A Level
  2. /Maths
  3. /2.4 Statistical Distributions

390 exam-style questions on OCR A Level Maths 2.4 Statistical Distributions, covering 2.4.1 Discrete probability distributions, 2.4.2 Binomial distribution as a model, 2.4.3 Calculating binomial probabilities, 2.4.4 Mean and variance of the binomial (A-level only), 2.4.5 Normal distribution as a model (A-level only), 2.4.6 Probabilities using the normal distribution (A-level only), 2.4.7 Links to histograms, mean and standard deviation (A-level only), and 2.4.8 Selecting an appropriate distribution (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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