SOLUTION: suppose that the frequency distibution of scores on an examination is closely described by a bell-shaped frequency curve and the distribution has a mean of 57.5 and a standard devi

Algebra ->  Probability-and-statistics -> SOLUTION: suppose that the frequency distibution of scores on an examination is closely described by a bell-shaped frequency curve and the distribution has a mean of 57.5 and a standard devi      Log On


   

Question 466005: suppose that the frequency distibution of scores on an examination is closely described by a bell-shaped frequency curve and the distribution has a mean of 57.5 and a standard deviation of 10
(i) what exam score would correspond to the standard score Z=2/3
(ii) what percentage of candidates would be awarded grade A if the cut-off for the grade A is 75 marks.
(iii) can a score of 20 marks be considered an out liar? explain your answer.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

z = (x-u)/s, 

x = zs + u

x = (2/3)10 +57.5

x = 64.17



z = (75-57.5)/10 = 1.75    NORMSDIST(1.75)= .9599  

 4% of candidates with an A



 mean 57.5, sd = 10  

Score of 20 nearly 4 sd left of mean...definitely an "out liar"