1,000 cars in the parking lot are surveyed and the average or
mean mileage is 30,000 on those cars. If the standard deviation
is 5,000, how many cars would fall in the range of mileage of
25,000 to 35,000 approximately? 1,000 cars in the parking lot
are surveyed and the average or mean mileage is 30,000 on those
cars. If the standard deviation is 5,000, how many cars would
fall For this question you need to remember the standard
deviation curve, commonly known as a bell curve. Here's a link
to one for reference:
http://statsdata.files.wordpress.com/2012/08/standard-d.gif. If
we have 30,000 miles as the average mileage (the center or mean
as its shown in the picture) between 1,000 cars with the
deviation being 5,000 miles (each s.d. on the picture), then our
bell curve will show that approximately 34.1% of the 1,000 cars
fall between 30,000 and 35,000 which is 341 cars (34.1% of
1000). We do the same going the other way, so between 25,000 and
30,000 miles there are 34.1% of the total 1,000 cars in that
deviati