A Company That Receives Most of Its Orders by Telephone

question 91

Multiple Choice

A company that receives most of its orders by telephone conducted a study to determine how long customers were willing to wait on hold before ordering a product.The length of waiting time was found to be a variable best approximated by an exponential distribution with a mean length of waiting time equal to 3 minutes (i.e.the mean number of calls answered in a minute is 1/3) .What proportion of customers having to hold more than 4.5 minutes will hang up before placing an order?

• A)0.22313
• B)0.48658
• C)0.51342
• D)0.77687

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Definitions:

Aortic Semilunar Valve

A valve in the heart located between the left ventricle and the aorta that prevents blood from flowing back into the heart after it has been ejected.

Chordae Tendineae

Tendon-like cords in the heart that connect the papillary muscles to the tricuspid valve and the mitral valve, preventing their inversion during contraction.

Trabeculae Carneae

Irregular muscular columns that line the interior walls of the ventricles of the heart.

Pectinate Muscles

Internal ridges of myocardium in the atria of the heart.