Answer Happy

3. (a) The sales manager of a chain store studies the difference between the mean daily sales of two new stores. It is known that the population standard deviations of daily sales of the two new stores are $500 and $480 respectively. If he wants to produce a point estimate of the difference between the two population means with error not more than $100 with 95% confidence, determine the required sample size when sample sizes are identical. [5 marks) 3 (b) The number of customers visiting the website of an online shopping store has a Poisson distribution with a mean of 4.25 per hour. i. In a randomly selected hour, what is the probability that less than 3 cus- tomers visit the website? [3 marks ii. In a randomly selected hour, what is the probability that 6 or more cus- tomers visit the website? [3 marks) iii. For live consecutive hours, what is the probability to have 2 consecutive hours with 6 or more customers and 3 other consecutive hours with less than 3 customers visit the website in each hour? [4 marks iv. With suitable approximation, find the probability that the total number of customers visit the website for the next 48 consecutive hours is less than 200. (5 marks]