An employee in a large corporation receives an average of mu = 41.7 e-mails per

Question

An employee in a large corporation receives an average of mu = 41.7 e-mails per day. Most of these e-mails are from other employees in the company. Because of the large number of e-mails, employees find themselves distracted and are unable to concentrate when they return to their tasks. In an effort to reduce distraction caused by such interruptions, one company established a priority list that all employees were to use before sending an email. One month after the new priority list was put in place a random sample of 45 employees showed that an average of mu = 36.2 e-mails per day. The computer server through which the e-mail is routed showed that sigma = 18.5. Has the policy had any effect? State the null and alternative hypothesis and use a 5%-level of significance to test the claim that there has been a change (either way) in the average number of e-mails received per day per employee.

Explanation / Answer

Null and Alternative Hypothesis:

H0: µ = 41.7

H1: µ ¹ 41.7

Level of significance = 0.05

Test Statistics:

z = (x bar – Mew) / (sigma/sqrt (n))

   = (36.2 – 41.7)/(18.5/sqrt(45))

   = -1.99

From normal table at 5% level of significance we got the critical values as -1.96 and + 1.96.

Test statistics -1.99 is less than -1.96; there is sufficient evidence to conclude that there has been a change in the average number of emails received per day per employee.

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