a) A manufacturer of floor wax has developed two new brands, A and B. To determine which of the
two is superior, both waxes are applied to the floor surfaces in each of a sample of 25 homes. It is
known that the proportion of people that prefer A is 0.7 while the rest prefer brand B. Find the
probability that at least 8 homes would state a preference for brand B.
b) The average number of persons entering a hospital casualty ward per hour is 9. Assume the
distribution of hospital casualty ward entries per hour can be approximated by the Poisson
probability distribution. What is the probability at most 4 people will enter the hospital casualty
ward in the next half an hour?
c) For a particular advertisement, there is a 10% chance of receiving a $5 return, a 30% chance of
receiving a $2 return, and a 60% chance of receiving a -$8 return. Calculate the expected return for
the advertisement.