Skip to content
MathsGenie logo
Quick links
Open app

Course home

  1. A Level
  2. Maths OCR (MEI)
  3. Question bank

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

EasyMediumHard
12345
Question 5

The mass of the wing case of a mature Emerald Beetle, WWW mg, is modeled by a normal distribution with a mean of 180 mg180\text{ mg}180 mg and a standard deviation of 12 mg12\text{ mg}12 mg.

a.

Determine the probability that the wing case of a randomly captured Emerald Beetle has a mass exceeding 207 mg207\text{ mg}207 mg.

[2]
b.

A specimen is classified as 'undersized' if its wing case mass is in the bottom 1.5%1.5\%1.5% of the population. Calculate the maximum mass, www, for a wing case to be classified as undersized.

[3]
c.

The mass of the wing case of a Ruby Beetle, MMM mg, is modeled by a normal distribution with mean μ\muμ and standard deviation σ\sigmaσ.

Research indicates that P(M<165)=0.04P(M < 165) = 0.04P(M<165)=0.04 and P(M>210)=0.015P(M > 210) = 0.015P(M>210)=0.015. Find the value of μ\muμ and the value of σ\sigmaσ, giving your answers to two decimal places.

[5]

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)