A four-day charity fundraiser received 53 donations on the first day, 49 donations on the second day, 43 donations on the third day, and 63 donations on the final day. What was the mean number of donations per day?

mean = 52

Step-by-step explanation:

Just add all four together and divide by 4. That's the mean.

Sum (49 + 43 + 53 + 63)/4 = 208

Mean = 208 /4 = 52

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