CAIE S1 2017 March — Question 7

Exam BoardCAIE
ModuleS1 (Statistics 1)
Year2017
SessionMarch
TopicNormal Distribution
TypeStandard two probabilities given

7
  1. The lengths, in centimetres, of middle fingers of women in Raneland have a normal distribution with mean \(\mu\) and standard deviation \(\sigma\). It is found that \(25 \%\) of these women have fingers longer than 8.8 cm and \(17.5 \%\) have fingers shorter than 7.7 cm .
    1. Find the values of \(\mu\) and \(\sigma\).
      The lengths, in centimetres, of middle fingers of women in Snoland have a normal distribution with mean 7.9 and standard deviation 0.44. A random sample of 5 women from Snoland is chosen.
    2. Find the probability that exactly 3 of these women have middle fingers shorter than 8.2 cm .
  2. The random variable \(X\) has a normal distribution with mean equal to the standard deviation. Find the probability that a particular value of \(X\) is less than 1.5 times the mean.