Question 665592
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Hi,

You didn't say how You determine the P-value of the z-value found
&#956; =650   &#963; = 100
P(  450<x< 850) =  P({{{z = (850-650)/100}}}) - P({{{z = (450-650)/100}}})
Out of 1000 randomly selected test scores, how many would you expect to be 
P(550 < x < 950) = P({{{z = (950-650)/(100/sqrt(1000))}}}) -  P({{{z = (550-650)/(100/sqrt(1000))}}})
Re TY:  In the case of 'multiplying' each data item by 5: 
mean is 5 times greater as well as is the standard deviation 5 times greater .