The distribution of the scores on a certain exam is N(70,10), which means that t

Question

The distribution of the scores on a certain exam is N(70,10), which means that the exam scores are Normaly distributed with a mean of 70 and standard deviation of 10 a. Sketch the curve and label, on the x-axis, the position of the mean, the mean plus or minus one standard deviation, the mean plus or minus two standard deviations, and the mean plus or minus three standard deviations. b. Find the probability that a randomly selected score will be greater than 90. Shade the region under the Normal curve whose area corresponds to this probability. A. B. C. 40 65 80 1 50 70 80 90 100 50 90 b. What is the probability that a randomly selected score will be greater than 90? Using the Empirical Rule, the probability that a randomly selected score will be greater than 90 is about Type an integer or a decimal.) Which graph shows the distribution with the region shaded under the Normal curve whose area corresponds to the probabity that a randomly selected score is greater than 90? O B. O C. 0 90 1 90 1

Explanation / Answer

mean is 70 and s is 10

z is (x-mean)/s

b. for P(x>90)=P(z>(90-70)/10)=P(z>2) or 1-P(z<2), from normal distribution table it is 1-0.9772=0.0228

answer is C

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