The upper arm length of females over 20 years old in a country is approximately Normal with mean 35.6 centimeters (cm) and standard deviation 2.3 cm. Use the 68-95-99.7 rule to answer the following questions. (Enter your answers to one decimal place.)

a. What range of lengths (±0.1 cm) covers almost all (99.7%) of this distribution?
b. What percent (±0.1%) of women over 20 have upper arm lengths below 33.5 cm?

answer:

what are the other choices

Step-by-step explanation:

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4