Percentile for z = +1
In a normal distribution, a score with z = +1 falls at about which percentile?
Answer C: explanation for every choice
A
The 50th percentile is the mean, z = 0.
B
68% of scores fall within ±1 SD of the mean. That isn't a percentile.
C
Correct. 50% fall below the mean and another 34% between the mean and +1 SD, for about 84%.
D
The 97.5th percentile corresponds to z ≈ +2.
TakeawayAbout 68% within ±1 SD, 95% within ±2 SD.
Equation usedz-score
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