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9966 [12]
3 years ago
11

Scores on an exam follow an approximately Normal distribution with a mean of 76.4 and a standard deviation of 6.1 points. What p

ercent of students scored below 95 points?
Mathematics
1 answer:
klasskru [66]3 years ago
5 0

Answer:

99.89% of students scored below 95 points.

Step-by-step explanation:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

Z = \frac{X - \mu}{\sigma}

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:

\mu = 76.4, \sigma = 6.1

What percent of students scored below 95 points?

This is the pvalue of Z when X = 95. So

Z = \frac{X - \mu}{\sigma}

Z = \frac{95 - 76.4}{6.1}

Z = 3.05

Z = 3.05 has a pvalue of 0.9989.

99.89% of students scored below 95 points.

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Answer:

Part A:

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Part B:

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Step-by-step explanation:

Part A:

The surface area of a cylinder is given by

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Already done above.

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Start by defining variables (things you don't know). Let's make:
t = number of true/false questions
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total questions on the test (given to be 20) is then:
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Equation #2
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m = 5

There are 5 multiple choice questions on the test.
Now use this to find t.
t + m = 20 
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t = 20 - 5
t = 15

there are 15 true/false questions on the test.
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