A professor at a local university noted that the grades of her students were nor
ID: 3043041 • Letter: A
Question
A professor at a local university noted that the grades of her students were normally distributed with a mean of 76 and a standard deviation of 10.
9. The professor has informed us that 16.6 percent of her students received grades of A. What is the minimum score needed to receive a grade of A?
85.7
87.7
88.3
88.7
10. If 12.1 percent of her students failed the course and received F's, what is the maximum score among those who received an F?
63.1
64.3
65.4
66.3
11. A subset of a population selected to represent the population is
a subset
a small population
a sample
a parameter
12. The phenomenon that the sampling distribution of the sample mean can be approximated by a normal distribution as the sample size become large is called
the neutral theorem
the sampling theorem
the central limit theorem
the normal distribution theorem
Explanation / Answer
mean is 76 and s is 10
a) for top 16.6% we need to look at the value that is 1-0.166 i.e 0.834 from left of the curve. for 0.834 the z value is 0.97 from normal distribution table. thus answer is 76+10*0.97 =85.7 or option A
b) for 0.121, the z value from normal curve is negative of that for 1-0.121 =0.879 or it is -1.17 , thus it is 76-1.17*10=64.3 or option B
c) option C (sample)
d) option C (central limit theorem)
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