# problem-7.17

problem-7.17 To properly make such a statistical inference, we assume that we can treat the data as a random sample from the population of visible (with the aid of a telescope) stars and then use the sample to make an estimate for the mean brightness of these stars.
First, we make a histogram, to check that the sample appears to come from a normally distributed population. Once this is verified, then t.test() can be used to find the desired confidence interval.

    > hist(brightness)              # looks good
    > t.test(brightness, conf.level = 0.90)
    ...
    90 percent confidence interval:
     8.349 8.486
    ...

For reference: in most suburbs the human eye can see stars with a brightness of 5.5 or less of which about 2,800 exist.