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2.4 Probability Distributions

2.4 Probability Distributions

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Question 239

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 Probability Distributions Questions

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

390 exam-style questions on OCR (MEI) A Level Maths 2.4 Probability Distributions, covering 2.4.1 Recognise binomial situations, 2.4.2 Probability of success p, 2.4.3 Calculate binomial probabilities, 2.4.4 Mean of the binomial distribution, 2.4.5 Expected frequencies for binomial, 2.4.6 Probability functions and discrete random variables, 2.4.7 Numerical probabilities for a simple distribution, 2.4.8 Normal distribution as a model (A-level only), 2.4.9 Shape of the Normal curve (A-level only), 2.4.10 Linear transformation and standardising (A-level only), 2.4.11 Symmetry and inflection of Normal curve (A-level only), 2.4.12 Calculate probabilities from a Normal distribution (A-level only), 2.4.13 Model with probability distributions, and 2.4 Probability Distributions. Each one has a worked solution and a mark scheme showing where the marks go.

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