To find the least amount of points a student must score to earn a D, we need to determine the z-score that corresponds to the 30th percentile (since the bottom 10% receive F's and the next 20% receive D's). Using a z-table or calculator, we find that the z-score for the 30th percentile is approximately -0.52.
Now, we can use the z-score formula to find the corresponding raw score:
z = (X - μ) / σ
where z is the z-score, X is the raw score, μ is the mean, and σ is the standard deviation.
Plugging in the values, we get:
-0.52 = (X - 72) / 9
Now, we can solve for X:
X - 72 = -0.52 * 9
X - 72 = -4.68
X = 67.32
So the least amount of points a student must score on the final exam to earn a D is approximately 67.32 points.
In a large section of a statistics class, the points for the final exam are normally distributed, with a mean of 72 and a standard deviation of 9. Grades are to be assigned according to the following rule:
The top 10% receive A's.
The next 20% receive B's.
The middle 40% receive C's.
The next 20% received D's.
The bottom 10% receive F's
What is the least amount of points that a student must score, on the final exam, in order to earn a D? (Round your answer to two decimal places.)
67.32 is the answer
1 answer
1 answer