Acustomer service phone line claims that the wait times before a call is answered by a service representative is less than 3.3 minutes. in a random sample of 62 calls, the average wait time before a representative answers is "3.24" minutes. the population standard deviation is assumed to be 0.40 minutes. can the claim be supported at α=0.08?

Step-by-step explanation:

Let x be the wait times before a call is answered in phone calls.

The claim is x bar <3.3 minutes

Sample size n =62

Sample mean - x bar = 3.24 minutes

Population std dev =

Since population std dev is known and also sample size is sufficiently large, we can use Z test.

(one tailed test)

Mean difference = 3.24-3.3 = -0.06 min

Std error of sample =

Z = tset statistic =

p value = 0.119

Since p value > alpha, we accept null hypothesis.

There is no evidence to support the claim at alpha = 0.08

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4