there are 320 seniors at strong field high school. if 90% of them go expect to go to college, how many of the seniors expect to
2 answers:
288. to figure this out I set up a proporton, 90 (percent) over 100 ( percentages are always out of 100) and x ( the variable, what's ere trying to figure out) over 320 (since we are trying to find what over 320 is equal to 90 out of 100.
after cross multiplying, you find that 90/100 is equal to 288/320
after cross multiplying, you find that 90/100 is equal to 288/320
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Answer:
There is a 95% chance that values will be within ±2 standard deviations of the mean.
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.
The Empirical Rule states that, for a normally distributed random variable:
Approximately 68% of the measures are within 1 standard deviation of the mean.
Approximately 95% of the measures are within 2 standard deviations of the mean.
Approximately 99.7% of the measures are within 3 standard deviations of the mean.
In this question:
According to the empirical rule, 95% of the measures are within 2 standard deviations of the mean. So the correct statement is:
There is a 95% chance that values will be within ±2 standard deviations of the mean.