80 is what percent of 120
2 answers:
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Answer:
2.28% of the class has a lower heart rate
Step-by-step explanation:
Problems of normally distributed samples can be solved using the z-score formula.
In a set with mean and standard deviation(which is the square root of the variance)
, the zscore 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 pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:
What percent of the class has a lower heart rate
Lower than 72, which is the pvalue of Z when X = 72.
has a pvalue of 0.0228
2.28% of the class has a lower heart rate