a) level of significance =0.05
b)
Test statistic =s12/s22 = | 2.54 |
dfN=21-1 = | 20 |
dfD=21-1 = | 20 |
c)
\
d)
e)
You don't need to be rich to buy a few shares in a mutual fund. The...
You don't need to be rich to buy a few shares in a mutual fund. The question is, how reliable are mutual funds as investments? This depends on the type of fund you buy. The following data are based on information taken from a mutual fund guide available in most libraries. A random sample of percentage annual returns for mutual funds holding stocks in aggressive-growth small companies is shown below. -1.2 14.1 41.7 17.6 -16.7 4.4 32.6 -7.3 16.2 2.8...
A random sample of leading companies in South Korea gave the following percentage yields based on assets. 2.1 2.3 4.2 1.9 0.5 3.6 2.4 0.2 1.7 1.8 1.4 5.4 1.1 Use a calculator to verify that s2 ≈ 2.125 for these South Korean companies. Another random sample of leading companies in Sweden gave the following percentage yields based on assets. 2.2 3.8 3.9 1.1 3.9 2.8 2.3 3.5 2.8 Use a calculator to verify that s2 ≈ 0.909 for these...
An economist wonders if corporate productivity in some countries is more volatile than in other countries. One measure of a company's productivity is annual percentage yield based on total company assets. A random sample of leading companies in France gave the following percentage yields based on assets. 4.2 5.5 3.6 3.9 2.7 3.5 2.8 4.4 5.7 3.4 4.1 6.8 2.9 3.2 7.2 6.5 5.0 3.3 2.8 2.5 4.5 Use a calculator to verify that the sample variance is s2 ≈...
An economist wonders if corporate productivity in some countries is more volatile than in other countries. One measure of a company's productivity is annual percentage yield based on total company assets. A random sample of leading companies in France gave the following percentage yields based on assets. 4.2 5.9 3.2 3.5 2.3 3.5 2.8 4.4 5.7 3.4 4.1 6.8 2.9 3.2 7.2 6.5 5.0 3.3 2.8 2.5 4.5 Use a calculator to verify that the sample variance is s2 ≈...
Rothamsted Experimental Station (England) has studied wheat production since 1852. Each year, many small plots of equal size but different soil/fertilizer conditions are planted with wheat. At the end of the growing season, the yield (in pounds) of the wheat on the plot is measured. For a random sample of years, one plot gave the following annual wheat production (in pounds). 4.29 3.90 3.99 3.87 4.29 3.79 4.09 4.42 3.89 3.87 4.12 3.09 4.86 2.90 5.01 3.39 Use a calculator...
Two plots at Rothamsted Experimental Station were studied for production of wheat straw. For a random sample of years, the annual wheat straw production (in pounds) from one plot was as follows. 6.96 7.10 5.84 5.91 7.31 7.18 7.06 5.79 6.24 5.91 6.14 Use a calculator to verify that, for this plot, the sample variance is s2 ≈ 0.384. Another random sample of years for a second plot gave the following annual wheat production (in pounds). 5.91 5.91 5.91 5.91...
Two plots at Rothamsted Experimental Station were studied for production of wheat straw. For a random sample of years, the annual wheat straw production (in pounds) from one plot was as follows. 6.33 5.84 5.98 5.77 7.31 7.18 7.06 5.79 6.24 5.91 6.14 Use a calculator to verify that, for this plot, the sample variance is s2 ≈ 0.340. Another random sample of years for a second plot gave the following annual wheat production (in pounds). 5.91 5.77 6.47 6.75...
A new fuel injection system has been engineered for pickup trucks. The new system and the old system both produce about the same average miles per gallon. However, engineers question which system (old or new) will give better consistency in fuel consumption (miles per gallon) under a variety of driving conditions. A random sample of 31 trucks were fitted with the new fuel injection system and driven under different conditions. For these trucks, the sample variance of gasoline consumption was...
A new fuel injection system has been engineered for pickup trucks. The new system and the old system both produce about the same average miles per gallon. However, engineers question which system (old or new) will give better consistency in fuel consumption (miles per gallon) under a variety of driving conditions. A random sample of 41 trucks was fitted with the new fuel injection system and driven under different conditions. For these trucks, the sample variance of gasoline consumption was...
A new thermostat has been engineered for the frozen food cases in large supermarkets. Both the old and new thermostats hold temperatures at an average of 25°F. However, it is hoped that the new thermostat might be more dependable in the sense that it will hold temperatures closer to 25°F. One frozen food case was equipped with the new thermostat, and a random sample of 26 temperature readings gave a sample variance of 5.2. Another similar frozen food case was...