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2.4.12 Calculate probabilities from a Normal distribution (A-level only)

2.4.12 Calculate probabilities from a Normal distribution (A-level only)

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Question 88

A tech logistics company monitors the flight duration of its delivery drones. The flight duration during the summer, S S\,S minutes, is modelled by a normal distribution S∼N(320,242)S \sim \text{N}(320, 24^2)S∼N(320,242).

a.

Using standardisation and showing your working, determine the probability that, for a drone flight selected at random in the summer,

(i) the duration exceeds 284 minutes,

(ii) the duration is 320 minutes, correct to the nearest 16 minutes.

[5]
b.

The flight duration during the winter, W W\,W minutes, is modelled by W∼N(μ,σ2)W \sim \text{N}(\mu, \sigma^2)W∼N(μ,σ2).

Given that P(W>280)=0.0901\text{P}(W > 280) = 0.0901P(W>280)=0.0901 and P(W<220)=0.2810\text{P}(W < 220) = 0.2810P(W<220)=0.2810,

(i) find two linear equations in terms of μ \mu\,μ and σ\sigmaσ,

(ii) hence, showing your working, calculate the value of μ \mu\,μ and the value of σ\sigmaσ.

[5]
Markscheme

2.4.12 Calculate probabilities from a Normal distribution (A-level only) Questions

  1. A Level
  2. /Maths
  3. /2.4.12 Calculate probabilities from a Normal distribution (A-level only)

149 exam-style questions on OCR (MEI) A Level Maths 2.4.12 Calculate probabilities from a Normal distribution (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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