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2 answers:
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Answer:
Z scores between -0.995 and 0.995 bound the middle 68% of the area under the stanrard normal curve
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean and standard deviation
, the z-score of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
Middle 68%
Between the 50 - (68/2) = 16th percentile and the 50 + (68/2) = 84th percentile.
16th percentile:
X when Z has a pvalue of 0.16. So X when Z = -0.995
84th percentile:
X when Z has a pvalue of 0.84. So X when Z = 0.995.
Z scores between -0.995 and 0.995 bound the middle 68% of the area under the stanrard normal curve
Answer:
6%
Step-by-step explanation:
- 90 + 60 = 150
- 7 + 2 = 9
- Set up a proportion:
- Cross multiply, then divide: 9 × 100 = 900, 900 ÷ 150 = 6
- So, 6% of students in 6th grade were left-handed
I hope this helps!