Undetermined coefficients with sines/cosines find a particular solution of the following equations. 17. y"-y 3 sin 2t 18, y" + 4y = 5 cos 3 t 19. y": sint + 3 cost 20. y"-3y'? 4y = 2 cos 2t-3 sin 2t

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?