Statistics Guide: Customers experiencing technical difficulty with their internet cable hookup may call an 800 number for technical support

Student Question: Customers experiencing technical difficulty with their internet cable hookup may call an 800 number for technical support. It takes the technician between 150 seconds and 12 minutes to resolve the problem. The distribution of this support time follows the uniform distribution.

What are the values for a and b in minutes?

The values of a and b represent the range of values in seconds. Simple multiply the number of minutes by 60 to find the total amount of seconds.

A = 150 seconds
B = 720 seconds

What is the mean time to resolve the problem?

Find the mean with the following formula: (150 + 720) / 2, which gives us 435.00 seconds.

Standard deviation?

The standard deviation of a range can be found  with the following formula: (720 – 150)/(Sqrt(12)), which gives us 164.5 seconds.

What percent of the problems take more than 5 minutes to resolve?

The percentage is found by using the following formula, (720-300)/(720-150), which gives us 73.68%. 

Setting up the Problem in Excel

It’s best to set up this problem in excel to quickly solve each value. Use the following image as a template for the formulas.

Excel template for qnt 351 week 2 technical difficulty problem


  • Student: Brandy Golden
  • Textbook: Business Statistics
  • Course: QNT 351

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