On the average, 6.7 cars arrive at the drive-up window of a bank ...

[waynest]

On the average, 6.7 cars arrive at the drive-up window of a bank every hour. Define the random variable x to be the number of cars arriving in any hour.
 a. What is the appropriate probability distribution for x? Explain how x satisfies the properties of the distribution.
  b. Compute the probability that exactly 5 cars will arrive in the next hour.
  c. Compute the probability that no more than 5 cars will arrive in the next hour.

Question 2

The 95 confidence interval estimate of a population variance when a sample variance of 324 is obtained from a sample of 81 items is
 a. 14.14 to 174.94.
  b. 243.086 to 453.520.
  c. 16.42 to 194.35.
  d. 254.419 to 429.203.

[af]

Answer to Question 1

a. Poisson; it shows the probability of x occurrences of the event over a time period.

b. 0.1385
c. 0.3406

Answer to Question 2

b