EXERCISE3.5 1. The management of a restaurant is considering closing one of its branches in Klang Valley. NS They need an estimate on the number of people who dine at the restaurant before making any decision. A sample of 30 days showed that an average of 450 people dine at the restaurant. The standard deviation of the population is known to be 10 people. Construct a 95% confidence interval for the mean number of people who dine at the restaurant. 2. In comparing the amount of caffeine intake between those who had trouble falling asleep and those who had not, a researcher took a random sample of 262 people and recorded necessary information. The data obtained were summarized as follows: One-Sample Statistics N Mean Sid. Deviation Std. Error Mean Amount of Caffeine 262 2.9427 1.92647 0.11902 Use this sample information to construct a 90% confidence interval for the mean amount of caffeine intake. 3. A manufacturer of a popular brand of bottled drink needs an estimate on the average volume of bottled drink that the company produces. Ten bottles of the same drink were chosen at random and their volumes (in millilitres) were recorded as follows: 495 491 501 502 497 496 499 500 501 503 a) Calculate the standard error of the mean. Hence, find the margin of error at 99% level of confidence. b) Construct a 99% confidence interval for the mean volume of bottled drink. 54 / 146