SAT verbal scores are normally distributed with a mean of 450 and a standard deviation of 120. Determine the percentage of scores falling between 450 and 570.
Mathematics · High School · Thu Feb 04 2021
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To determine the percentage of scores that fall between 450 and 570 on the SAT verbal section, which is normally distributed with a mean (μ) of 450 and a standard deviation (σ) of 120, we will use the standard normal distribution (Z- scores).
First, we need to convert the raw scores to Z-scores. The formula to calculate the Z-score for a value X is:
Z = (X - μ) / σ
Let's calculate the Z-scores for 450 and 570:
For X = 450 (which is the mean): Z_450 = (450 - 450) / 120 = 0
For X = 570: Z_570 = (570 - 450) / 120 = 120 / 120 = 1
Now, we want to find the area under the normal distribution curve between Z = 0 and Z = 1. This area represents the percentage of scores between 450 and 570.
We can use a standard normal distribution table, a calculator, or statistical software to find the area to the left of Z = 1. Typically, this value corresponds to a percentage (or probability) of 0.8413 or 84.13%.
Since a Z-score of 0 corresponds to the mean (which is 50th percentile), the percentage of scores between the mean and a Z-score of 1 is:
84.13% - 50% = 34.13%
Thus, approximately 34.13% of scores fall between 450 and 570 on the SAT verbal section.