0:00:00.000,0:00:05.000 And obviously the new mean is 1.2 times the old mean because we're multiplying 0:00:05.000,0:00:11.000 everything up by 20% raise that makes a factor of 1.2 over here and zero over here 0:00:11.000,0:00:15.000 because we don't really add a constant amount of money per person its variable. 0:00:15.000,0:00:19.000 It's a multiplicative change. For the variance it's more interesting. 0:00:19.000,0:00:27.000 In our new variance, we multiply each salary by a factor of 1.2 and the same is through for the mean. 0:00:27.000,0:00:34.000 When we look at this, we can bring the 1.2 outside these brackets and it becomes (1.2)². 0:00:34.000,0:00:40.000 The reason why I squared this, we can bring it outside Xi and u but there's a square over here 0:00:40.000,0:00:42.000 and we can move it outside this sum as a factor. 0:00:42.000,0:00:45.000 Now this is true for the variance but not the standard deviation. 0:00:45.000,0:00:48.000 The standard deviation is cleared of the variance. 0:00:48.000,9:59:59.000 The standard deviation was up by factor of 1.2 only, with a constant offset of zero.