١٤٣ III ١٢:١٠ م learn.ejust.org - خاص 3G Be Safe II. Q1. In an automobile plant two tasks are performed by robots. The first entails welding two joints; the second, tightening three bolts. Let X denote the number of defective welds and Y the number of improperly tightened bolts produced per car. Since X and Y are each discrete, (X, Y) is a discrete joint random variables. Past data indicates that the the joint density for (X, Y) is shown in the table below. (a) Find the probability that there will be exactly one error made. (b) The probability that there will be no improperly tightened bolts. y p(x, y) 0 1 2 3 0 0.840 0.030 0.020 0.010 X 1 0.060 0.010 0.0080.002 2 0.010 0.005 0.004 0.001