In a factory that produces wire, a spooling
machine is programmed to put 3550 feet of
wire on each spool.
The company ran the machine multiple times
and recorded how much wire was actually
placed on each spool. They found that the
mean length of wire was actually 3530 feet
with a standard deviation of 20 feet. Then
they ran the machine again to produce an
additional sample of 400 spools of wire.
Assume that the data is normally distributed
and use the 68-95-99.7 Rule to answer
the following questions.
a) How many spools from the sample of 400
have more than 3550 feet of wire?
spools
b) How many spools from the sample of 400
have between 3490 and 3570 feet of wire?
spools