An appliance manufacturer claims 10 have developed a compact microwave oven that

Question

An appliance manufacturer claims 10 have developed a compact microwave oven that consumes an average of no more than 250 W. From previous studies, it is believed that power consumption for microwave ovens is normally distributed with a standard deviation of 15 W. A consumer group has decided to try to discover if the claim appears true. They take a sample of 20 micro wave ovens and find that they consume an average of 257.3 W. Referring to Table 9-3, the population of interest is a) the power consumption in the 20 microwave ovens. b) the power consumption in all such microwave ovens. c) the mean power consumption in the 20 microwave ovens. d) the mean power consumption in all such microwave ovens. Referring to Table 9-3, the parameter of interest is a) the mean power consumption of the 20 microwave ovens. b) the mean power consumption of all such microwave ovens. c) 250 d) 257.3 Referring to Table 9-3, the appropriate hypotheses to determine if the manufacturer pears reasonable are: a) H_0: mu = 250 versus H_1: mu notequalto 250 b) H_0: mu greaterthanorequalto 250 versus H_1: mu 250 d) H_0: mu greaterthanorequalto 257.3 versus H_1: mu 257.3

Explanation / Answer

Solution:-

Given,

= 15 W
n = 20
x = 257.3 W

12. d) The mean power consumption in all such microwave ovens.

13. (a) The parameter of interest is the mean power consumption of the 20 microwave ovens.

14. (b) Ho >=250
Ha < 250

For if you need further calculations, for the value of z.

Using sample data, we compute, the degrees of freedom (DF), and the z test statistic (z).
DF = n - 1 = 20 - 1 = 19
z = (x - ) / = (257.3 - 250)/15 = 0.4867

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