n ice cream seller takes 20 gallons of ice cream in her truck each day. Let X stand for the number of gallons that she sells. The probability is 0.1 when X = 20. If she doesn’t sell all 20 gallons, the distribution of X follows a continuous distribution with pdf f(x) = cx if 0 < x < 20, where c is a constant that makes P(X < 20) = 0.9. What is the value of c?

9.4.34  question   to estimate the height of a stone  figure, an observer holds a small square up to her eyes and walks backward from the figure. she stops when the bottom of the figure aligns with the bottom edge of the  square, and when the top of the figure aligns with the top edge of the square. her eye level is 1.811.81 m from the ground. she is 3.703.70 m from the figure. what is the height of the figure to the nearest hundredth of a  meter?