The variance for the binomial probability distribution is _____. ...

[faduma]

The variance for the binomial probability distribution is _____.
 a. Var(x) = p(1  p)
  b. Var(x) = np
  c. Var(x) = n(1  p)
  d. Var(x) = np(1  p)

Question 2

Automobiles manufactured by the Efficiency Company have been averaging 42 miles per gallon of gasoline in highway driving. It is believed that its new automobiles average more than 42 miles per gallon. An independent testing service road-tested 36 of the automobiles. The sample showed an average of 42.8 miles per gallon with a standard deviation of 1.2 miles per gallon.
 a. With a .05 level of significance using the critical value approach, test to determine whether or not the new automobiles actually do average more than 42 miles per gallon.
  b. What is the p-value associated with the sample results? What is your conclusion based on the p-value?

[billybob123]

Answer to Question 1

d

Answer to Question 2

a. H0:  < 42 miles per gallon
Ha:  > 42 miles per gallon
Because t = 4.0 > 1.690, reject H0 and conclude that the new cars average more than 42 miles per gallon.
b. p-value < .005, therefore reject H0 (area to the right of t = 4.0 is almost zero) and conclude that the average is more than 42 miles per gallon for the new cars.