Question

Internet speeds are a heavily advertised selling point of Internet Service Providers. You notice that although you are paying for a certain speed, the true speed seems to vary depending on where you are in your house. In order to estimate the true average speed you are getting in your house, you go to 10 random spots around your house and record the speed (in MBs per second) shown from a test at 'www.speedtest.net'. You see that the average is 8.87 MB/s with a standard deviation of 1.174 MB/s. You decide to create a 95% confidence interval for the average internet speed in your house. What is the margin of error for this estimate?

Answer 1

At 95% confidence interval the critical value is t^* = 2.262

Margin of error = t^* * s/

                         = 2.262 * 1.174/

                         = 0.84

The 95% confidence interval for population mean is

+/- ME

= 8.87 +/- 0.84

= 8.03, 9.71