Suppose the scores on a grammar quiz are normally distributed with a mean of 76 and a standard deviation of 8.

Which group describes 16% of the population of grammar quiz scores?

a. scores below 60

b. scores below 68

c. scores above 80

d. scores above 94

Guest Apr 10, 2019

#1**+1 **

(always good to commit to memory the values of the standard bell curve...as shown above)

Similar Q has been posted multiple times. One standard deviation ABOVE 76 = 84 and has a z-score .8413 so approx 16% of the population is ABOVE this score ....but that does not fit the answers......so look at the NEGATIVE z-score table for the value nearest .16

Between -1.- and - 0.9 standard deviations represents this 16% ...I'll just use -1.0

76 - 1.0(8) = 68 scores below 68 represent 16% of the scores

ElectricPavlov Apr 10, 2019

#1**+1 **

Best Answer

(always good to commit to memory the values of the standard bell curve...as shown above)

Similar Q has been posted multiple times. One standard deviation ABOVE 76 = 84 and has a z-score .8413 so approx 16% of the population is ABOVE this score ....but that does not fit the answers......so look at the NEGATIVE z-score table for the value nearest .16

Between -1.- and - 0.9 standard deviations represents this 16% ...I'll just use -1.0

76 - 1.0(8) = 68 scores below 68 represent 16% of the scores

ElectricPavlov Apr 10, 2019