## Math 170A – Homework 1-Let A = {1, 3, 4, 5}

Math 170A – Homework 1 – Due 4 October 20161. Let A = {1, 3, 4, 5}, B = {2, 4, 6, 7} and C = {1, 4}. Find (A ? B) ? C c .2. Suppose that a 1 meter glass rod falls onto the floor and is broken into two pieces. Assumethat the breaking point is uniform between 0 and 1 meter. What is the probability thatthe longer piece has length at least 0.6 meter?3. Suppose that A and B are two events such that P(A) = 0.4, P(B) = 0.5 and P(A?B) = 0.6.Find P(A ? B).4. Let A, B, C be sets. Show that(i) A ? B c = A ? (A ? B)c and(ii) A ? C c ? (A ? B c ) ? (B ? C c ).5. If A1 and A2 are two sets, we define the symmetric difference A1 ?A2 byA1 ?A2 = (A1 ? Ac2 ) ? (A2 ? Ac1 ).(This is simply the set of all points that either in A or B but not both.) Show that(i) P(A1 ?A2 ) = P(A1 ) + P(A2 ) ? 2P(A1 ? A2 ) and(ii) for every sets A, B, C,P(A?C) ? P(A?B) + P(B?C).6. Suppose that I arrive at a bus stop at some time between 8:00 am and 8:25 am withuniform probability. Buses arrive at 8:03, 8:13, 8:23, 8:33,. . .. What is the probabilitythat I need to wait more than 2 minutes?