3. (30 points) In measuring reaction time, a psychologist estimates that the standard deviation is 0.05 seconds. How large a sample of measurements must be taken in order to be (a) 95% , (b) 99% and (c) 50% confident that the error in his estimate of mean reaction time will not exceed 0.02 second? (Hint: zc =2.58, = 1.96 zc= 0.6745 z table. is nearly normal Ez in 99 zc 95% distribute.) 50% % M AN