(Q6-Q7) Gillette recently announced plans to launch a new 3-edged razor, called the MACH3. The company spent 6 years and more than $750 million developing this razor. The new razor will sell for approximately $5 with replacement cartridges selling for $1.35 each, a 35% premium over Gillette's flagship two-blade Sensor razor. The Wall Street Journal (April 14, 1998) calls the product a "calculated gamble" and notes that "Gillette's master plan has little room for error".

6. Because of the great secrecy surrounding the development of the razor, Gillette has not done extensive market research. In fact, they have tested the new razor on a sample of only 100

members of the target population ("men who shave"), each of whom signed a non- disclosure agreement. In this sample, 65 indicated that they prefer the MACH3 to the Sensor razor. Use this sample data to construct a 95% confidence interval for the proportion of "men who shave" who prefer the MACH3 to the Sensor.

A. [0.572, 0.728]

B. [0.557, 0.743]

C. [0.49, 0.81]

D. None

7. Now that the razor has been announced, Gillette wants to gather more information to improve the accuracy of its market share estimates. Suppose Gillette wants to survey

enough "men who shave" to reduce the 95 percent confidence interval of part (a) to a width of 2%. How many "men who shave" must they sample?

A. 2401

B. 1692

C. 1667

D. None