SOLUTION: A class is given an exam. The distribution of the scores is normal. The mean score is 80 and the standard deviation is 11. What is the probability that a student scored less than 7

Question 1158684: A class is given an exam. The distribution of the scores is normal. The mean score is 80 and the standard deviation is 11. What is the probability that a student scored less than 78?
P(x < 78) =
Express the probability as a decimal rounded to 4 decimal places.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
z=(x-mean)/sd
=(78-80)/11
probability z<-2/11 is 0.4279
We usually use z in the decimal form so here z=-0.182, but on a calculator one can use the fraction just as well.
2VARS 2 Normalcdf -6, -(2/11) . Note, I use -6 rather than 1E99 just for simplicity since 6 sd s from the mean will not change the result to four decimal places.
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