Question

1)

The lifetime of 60W GE light bulbs are known to follow an exponential (skewed to the right) distribution. GE wants to test its own claim that the average lifetime of its 60W light bulbs is at least 1000 hours, so they test 10 bulbs at random (they don?t want to destroy too many) and calculate the mean and standard deviation of their sample. Which type of test should they perform?

		One-sample z-test since they know the true standard deviation of the light bulb lifetimes.
		One-sample t-test since they do not know the true standard deviation of the light bulb lifetimes.
		One-sample t-test since they do not know the true standard deviation of the light bulb lifetimes but they have a large sample.
		Neither One-sample z-test nor One-sample t-test.

Which of the following is TRUE when determining whether or not to apply the Central Limit Theorem?

		If the sampled population is normal, then the sampling distribution of the sample mean will also be normal, no matter what sample size is chosen.
		When the sampled population is approximately symmetric, the sampling distribution of the sample mean becomes approximately normal only when n is large (at least 30).
		When the sampled population is left skewed, the sampling distribution of the sample mean becomes approximately normal for relatively small values of n.
		When the sampled population is right skewed, the sampling distribution of the sample mean becomes approximately normal for relatively small values of n.

1. A random sample of 100 UAEU students was taken. Eighty of the students in the sample favored Hotmail services. The 95% confidence interval for the true proportion of students who favor Hotmail services is

   		0.722 to 0.878
   		0.762 to 0.838
   		78.04 to 81.96
   		62.469 to 97.531

If we reject H₀ at the 5% level, then

		we must also reject at the 1% level.
		we have a 5% chance of making a Type II error.
		then hypothesized value would not be in a 95% confidence interval calculated from the same data.
		then hypothesized value would be in a 95% confidence interval calculated from the same data.

Answer 1