1) A market research firm conducts telephone surveys with a 40% historical response rate.

• a) What is the sampling distribution, mean, and standard deviation of p , the proportion of individuals who respond to these surveys in a sample of 400 telephone numbers? Refer to Section 7.6 in your textbook.
• b) Calculate the probability that in a new sample of 400 telephone numbers, at least 150 individuals will cooperate and respond to the questions?

2) A production process is checked periodically by a quality control inspector. The inspector selects simple random samples of 30 finished products and computes the sample mean product weights x . Suppose test results over a long period of time show that 5% of the x values are over 2.1 pounds and 5% are under 1.9 pounds. Calculate the mean for the population of products produced with this process.