 # Historical Vs Expectional DATA

Hi, putting histrical data into BA II plus is easy, then you receive SD, mean, Variance in [STAT]; so you save your time during exam eg. expected returns in 2005 - 2007 are: 0.06; 0.09; 0.15 1. you put this data into your calc 2. then receive everything in STAT ( 2nd + “7”) mean = 0,1 SD for population = 0,03 variance for population = 0,0014 everything is nice and easy, but what about expectional data e.g. 50% chance for 0,2 return; 25% for 0,1 return; 25% for -0,1 return, and my question is: how to input this data to DATA sheet on BA II plus to receive: mean, SD on STAT mode? i’ve tried to input X1 = 0,5 * 0,2 ; X2 = 0,25 * 0,1; X3 = 0,25 * -0,10; but this is non sense, so is there any method not to do this my foot?

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Well you shouldn’t do this because the whole concept is dubious but since you’ve bumped it twice, it seems important for you to learn some high-tech way of missing these points on the exam so I might as well tell you. Put in sample statistics that exactly correspond to the distribution, which may not be easy but is always possible in discrete distributions with rational probabilities. Here, for example, enter into your machine as data 0.2, 0.2, 0.1,-0.1 and then calculate population means and variances. Notice half the sample is 0.2, 0.25 of the sample is 0.1, and 0.25 of the sample is -0.1, The general ruole is that you are going to have to enter as many numbers into your calculator as the smallest integer which when multiplied by each of the probabilities gives you an integer. Here it is 4. Now if your probabilities are e/6, e/7, 1- (e/6 +e/7) then you have a problem.