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Study results indicate that the mean length of time people spend on a bus in a city is between 22.4 minutes and 26.5 minutes.

What is the study's margin of error?

2.05 min

3.25 min

4.1 min

8.2 min

Dec 11, 2019

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$$(22.4, 26.5)$$is caalled a confidence interval. The way you form a confidence interval is by adding and subtracting the margin of error from the sample mean. so

$$26.5=sample\ mean+margin\ of\ error$$, and

$$22.4=sample\ mean-margin\ of\ error$$.

Solve the system of equations by adding the two equations to eliminate margin of error and get

$$2\times sample\ mean=22.4+26.5=48.9$$, or

$$sample\ mean=\frac{48.9}{2}=24.45$$.

So $$margin\ of\ error=26.5-24.45=2.05$$

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Dec 12, 2019