Question 924195
mean of 1650 kilowatt-hours and a standard deviation of 320 kilowatt-hours. 
Note: {{{z = blue(x - 1650)/blue(320)}}}    
P( x < 1900) = 9( z < 250/320) = P( z < .7813) = P(-100, .7813) = .7827
Using a TI or Similarly a Casio fx-115 ES plus