Ex. 1. If weekly wage of 10,000 workers in a factory follows normal distribution with a mean and s.d. Rs. 70 and Rs. 5 respectively, find the expected number of workers whose weekly wages are (i) between Rs. 66 and Rs. 72 (ii) less than Rs. 66 (iii) more than Rs. 72
[ Given that 1/√2Π 0∫Πe-t2/2 dt = 0.1554 and 0.2881 according as z=0.4 and z=0.8 ]
Ex. 2. The mean of a normal distribution is 50 and 5% of values are greater than 60. Find the standard deviation of the distribution (Given that the area under normal curve between z=0 and z= 1.64 is 0.45)