The scores on a test given to all juniors in a school district are normally distributed with a mean of 72 and a standard deviation of 6. find the probability that a randomly chosen junior has a score above 90. the probability of randomly choosing a junior whose score is above 90 %.

answer   download the app called socratic on your phoner:

step-by-step explanation:

do you have a picture of the table

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