The results of a chemistry examination are normally distributed with a mean score of 56 and a standard deviation of 12. What is the percentage probability that a student will score more than 80?
the answer is
28% Z-score = (x -?)/? Therefore: (80 –56)/12 = 2 From the normal distribution table, 2 = 0.4772 To find the probability of scoring more than 80: 0.5 –0.4772 = 0.0228 or 2.28% as a %.
where does the 0.5 come from? is it always 0.5 in these questions?