1. Use technology to find critical values for T-distribution. Round your answers to three decimal places.

1(a). Confidence level 95%, sample size 21. T_c =

1(b). Confidence level 90%, sample size 25. T_c =

1(c). Confidence level 99%, sample size 30. T_c =

1(d). Confidence level 98%, sample size 8. T_c =

2. The following data give the speeds (in miles per hour), as measured by radar, of 14 cars traveling on Interstate I-5. Assume the speeds of all cars traveling on this highway is approximately normally distributed.

76, 76, 80, 68, 76, 78, 83, 87, 79, 85, 76, 81, 79, 82

Answer parts (a) through (c).

2(a). Determine the sample mean, sample standard deviation, and sample size.

x =

s = (Round to two decimal places)

n = 2(b). Determine the critical value that corresponds to the 98% level of confidence, and compute the margin of error.

T_c = (Round to two decimal places)

m = (Round to one decimal place)

2(c). Construct a 98% confidence interval for the mean speed of cars traveling on I-5. Round your values to one decimal place.

<<