SOLUTION: 17. A group of students at a school takes a history test. The distribution is normal with a mean of 25, and a standard deviation of 4. a. Everyone who scores in the top 30% of t

Question 1012460: 17. A group of students at a school takes a history test. The distribution is normal with a mean of 25, and a standard deviation of 4.
a. Everyone who scores in the top 30% of the distribution gets a certificate. What is the lowest score someone can get and still earn a certificate?
b. The top 5% of the scores get to compete in a statewide history contest. What is the lowest score someone can get and still go onto compete with the rest of the state?
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
Mean 25
sd=4
z0.70=0.525
z=(x-mean)/sd
z*sd=x-mean=2.1
x=27.1 is the minimum score for the top 30%.
top 5% has a z0,95=1.645
That * sd of 4=6.580
added to mean, and that score is 31.58
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