81.0k views
1 vote
5. The length of time between billing dates and checks received and deposited for non-delinquent accounts of an oil company’s monthly credit card customers is 13.5 days with a standard deviation of 3 days. A bank claims if the company used a lockbox system, it could reduce the company’s average time. Thirty-six (36) accounts were randomly selected and tested using the lockbox system. The average time was found to be 13 days. What is your conclusion at the 2.5% level of significance?

User Gavy
by
8.0k points

1 Answer

3 votes

Answer:

Explanation:

Let X be the length of time between billing dates and checks received and deposited for non-delinquent accounts of an oil company’s monthly credit card customers

X has mean 13.5 and sigma 3 days

Sample size = n =36, x bar = 13


H_0: x bar = 13.5\\H_a: x bar <13.5

(One tailed test at 0.025 sign. level)

Mean diff = -0.5

Since sigma is known z test can be used

Std error =
(\sigma)/(√(n) ) =0.5

Z statistic = -0.5/SE= -0.1

p value = 0.920

p>0.025 hence accept null hypothesis.

My conclusion is there is no statistical evidence that lock box reduced the mean time.

User Muniro
by
8.7k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.