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

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Question 25

A drone delivery company, AirLift, categorizes items into two types: Priority (PPP) and Standard (SSS). The masses, in grams, of Priority packages are distributed as P∼N(820,202)P \sim \text{N}(820, 20^2)P∼N(820,202) and the masses of Standard packages are distributed as S∼N(610,122)S \sim \text{N}(610, 12^2)S∼N(610,122).

a.

A Priority package and a Standard package are selected at random. Determine the probability that the mass of the Priority package is less than 135%135\%135% of the mass of the Standard package.

[5]
b.

Two Standard packages are chosen at random. Find the probability that the absolute difference between their masses is more than 181818 g.

[4]
c.

AirLift uses protective shipping crates to transport goods. Each crate contains either 666 Priority packages or 888 Standard packages. The mass of an empty shipping crate, MMM, is distributed as M∼N(150,102)M \sim \text{N}(150, 10^2)M∼N(150,102). Determine the probability that a crate of 888 Standard packages has a greater total mass than a crate of 666 Priority packages.

[6]

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

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