OCR H240/02 2019 June — Question 9

Exam BoardOCR
ModuleH240/02 (Pure Mathematics and Statistics)
Year2019
SessionJune
TopicNormal Distribution
TypeDirect binomial from normal probability

9
  1. The masses, in grams, of plums of a certain kind have the distribution \(\mathrm { N } ( 55,18 )\).
    1. Find the probability that a plum chosen at random has a mass between 50.0 and 60.0 grams.
    2. The heaviest \(5 \%\) of plums are classified as extra large. Find the minimum mass of extra large plums.
    3. The plums are packed in bags, each containing 10 randomly selected plums. Find the probability that a bag chosen at random has a total mass of less than 530 g .
  2. The masses, in grams, of apples of a certain kind have the distribution \(\mathrm { N } \left( 67 , \sigma ^ { 2 } \right)\). It is given that half of the apples have masses between 62 g and 72 g . Determine \(\sigma\).