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2 Statistics

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Question 199

An entomologist studies the wingspans of a specific species of hawk moth. The wingspans, SSS millimetres, are normally distributed with a mean of 42 mm42\text{ mm}42 mm and a standard deviation of 6 mm6\text{ mm}6 mm.

a.

Estimate the proportion of these moths that have a wingspan greater than 51 mm51\text{ mm}51 mm.

[2]
b.

The entomologist classifies the moths into three categories: Narrow, Average, and Wide, such that there is an equal proportion of moths (exactly 13\frac{1}{3}31​) in each category.

Determine the range of wingspans that defines the 'Average' category.

[4]
c.

A moth is selected at random from the 'Wide' category.

Find the probability that this moth's wingspan is less than 48 mm48\text{ mm}48 mm.

[3]
d.

A researcher collects a random sample of 3 moths from the population.

Find the probability that there is exactly one moth from each of the three categories.

[2]
Markscheme

2 Statistics Questions

  1. A Level
  2. /Maths
  3. /2 Statistics

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