Refer to problem BELOW. Belkin Products obtained 18 observations of the output voltages for a particular power supply unit. For these data, while solving problem 2) above, you have obtained (the point estimate of µ) and s (the point estimate for ¬). Now, for problem 3), how large a sample would the firm need for to be within .2 volts of the actual average output voltage with 95% confidence?
The output voltage of power supplies manufactured by Belkin Products is believed to follow a normal distribution. Of primary concern to the firm is the average output voltage of a particular power supply unit, believed to be 10 volts. Eighteen observations taken at random from this unit are as given below: