SOLUTION: the results of a statewide exam for assessing the mathematics skills of realtors were normally distributed with a mean score of 72 and a standard deviation of 12. The realtors who

Question 1122525: the results of a statewide exam for assessing the mathematics skills of realtors were normally distributed with a mean score of 72 and a standard deviation of 12. The realtors who scored in the top 10% are to receive a special certificate, while those in the bottom 20% will be required to attend a remedial workshop.
a. what score does a realtor need in order to receive a certificate?
b. What score will dictate that the realtor attend the workshop?

Don't know where to start on this problem
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
z=(x-mean)/sd
top 10% is 0.9000 in the z-table, and z=1.28
therefore 1.28=(x-mean)/sd for cut off top score
1.28=(x-mean)/12
15.36=x-72
x=87.36, cut off for top score
Bottom 20% (draw std normal curve) is at z=-0.84
so-0.84=(x-72)/12
-10.08=x-72
x=61.92, cut off score below which remedial must be attended.
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