In developing a confidence interval estimate for the population mean, the t-distribution is used to ...

In developing a confidence interval estimate for the population mean, the t-distribution is used to obtain the critical value when:
 
  A) the sample contains some extreme values that skew the results.
  B) the population standard deviation is unknown.
  C) the sampling that is being used is not a statistical sample.
  D) the confidence level is low.

Q. 2

A typical charity raffle involves selling one thousand 50 tickets to win a 30,000 grand prize. If the probability of winning is only 0.002, what is the expected payoff?
 
  A) (35.50 )
  B) 25.65
  C) (50.25 )
  D) 10.10

Q. 3

If a continuous random variable is said to be exponentially distributed, what would be the easiest way to reduce the standard deviation?
 
  What will be an ideal response?

Q. 4

In a situation where the population standard deviation is known and we wish to estimate the population mean with 90 percent confidence, what is the appropriate critical value to use?
 
  A) z = 1.96
  B) z = 2.33
  C) z = 1.645
  D) Can't be determined without knowing the degrees of freedom.