You have a ruler of length 2 and you choose a place to break it using a uniform probability distribution. let random variable x represent the length of the left piece of the ruler. x is distributed uniformly in [0,2] . you take the left piece of the ruler and once again choose a place to break it using a uniform probability distribution. let random variable y be the length of the left piece from the second break. draw a picture of the region in the x-y plane for which the joint density of x and y is non-zero.

Hi!

When you break the rule for the first time, de probability distribution of X is constant in [0, 2], and is zero outside. If the the value obtained is X = a, then the probability distribution of Y (conditioned on X = a) is constaint in interval [0, a], and zero outside. Then the region in the X-Y plane where the joint density is non-zero is the filled triangle  in the figure.

well if he bought them at 5 cedis each sold them at 7 cedis each then he would make a profit of 2 cedis of each book. if in total he made 150 cedis profit that means he sold 75 books. he lost 12 books at the start so that means he originally bought a total of 82 books.

step-by-step explanation:

i think the answer is 90 hope this