Question

The Buffalo, New York, Chamber of Commerce wants to estimate the mean time workers who are employed in the downtown area spend getting to work. A sample of 15 workers reveals the following number of minutes spent traveling.

14	24	24	19	24	7	31	20	26	23	23	28	16	15	21

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Develop a 98% confidence interval for the population mean. (Round your answers to 2 decimal places.)

Answer 1

The 98% confidence interval for teh data will be calculated using the formula:

, where is the criticl value of t at 98% n is the number of observations and s is the standard deviation of the data and is the mean of the data. We shall calculate mean by using the formula

and

We need to square the individual observation and add them to find the values. We use the following table for this.

	Time	X^2
	14	196
	24	576
	24	576
	19	361
	24	576
	7	49
	31	961
	20	400
	26	676
	23	529
	23	529
	28	784
	16	256
	15	225
	21	441
Total	315	7135

Hence the

  

  

The 98% confidence interval for the population mean=(16.87,25.13).