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Scilla [17]
2 years ago
5

The scores of students on a standardized test are normally distributed with a mean of 300 and a standarddeviation of 40.

Mathematics
1 answer:
spin [16.1K]2 years ago
7 0

Answer:

a) 0.9544 = 95.44% of scores lie between 220 and 380 points.

b) 0.1587 = 15.87% probability that a randomly chosen student scores is below 260.

c) 25.14% of scores are above 326.8 points.

Step-by-step explanation:

Normal Probability Distribution

Problems of normal distributions can be solved using the z-score formula.

In a set with mean \mu and standard deviation \sigma, the z-score 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 p-value, we get the probability that the value of the measure is greater than X.

Mean of 300 and a standard deviation of 40.

This means that \mu = 300, \sigma = 40

(a) What proportion of scores lie between 220 and 380 points?

This is the p-value of Z when X = 380 subtracted by the p-value of Z when X = 220.

X = 380

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

Z = \frac{380 - 300}{40}

Z = 2

Z = 2 has a p-value of 0.9772.

X = 220

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

Z = \frac{220 - 300}{40}

Z = -2

Z = -2 has a p-value of 0.0228.

0.9772 - 0.0228 = 0.9544

0.9544 = 95.44% of scores lie between 220 and 380 points.

(b) What is the probability that a randomly chosen student scores is below 260?

This is the p-value of Z when X = 260. So

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

Z = \frac{260 - 300}{40}

Z = -1

Z = -1 has a p-value of 0.1587.

0.1587 = 15.87% probability that a randomly chosen student scores is below 260.

(c) What percent of scores are above 326.8 points?

The proportion is 1 subtracted by the p-value of Z when X = 326.8. So

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

Z = \frac{326.8 - 300}{40}

Z = 0.67

Z = 0.67 has a p-value of 0.7486.

1 - 0.7486 = 0.2514

0.2514*100% = 25.14%

25.14% of scores are above 326.8 points.

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There are 20 baseball cards and 10 football cards on display at a sports museum. Noah says that
erica [24]

Answer:

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Step-by-step explanation:

6 0
2 years ago
In a certain exam of grade ten, 75% students got high score in mathematics, 65%
faltersainse [42]

(i) The percentage of students who got high scores in both the subjects English and Mathematics is 46%.

(ii) The total number of students who got high scores either in Mathematics or in English if 300 students had attended the exam exists 138.

<h3>What is probability?</h3>

The probability exists in the analysis of the possibilities of happening of an outcome, which exists acquired by the ratio between favorable cases and possible cases.

The number of students who got high scores in Mathematics was 75%.

The number of students who got high scores in English was 65%.

(i) The percentage of students who got high scores in both the subjects

100% - 6% = 94%

(75% + 65%) - 94%

= 140% - 94%

= 46%

Therefore, the percentage of students who got high scores in both the subjects English and Mathematics is 46%.

(ii) The total number of students who got high scores either in Mathematics or in English if 300 students had attended the exam

= 300 * 46%

= 300 * (46 / 100)

= 300 * 0.46

= 138.

Therefore, the total number of students who got high scores either in Mathematics or in English if 300 students had attended the exam exists 138.

To learn more about probability refer to:

brainly.com/question/13604758

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6 0
1 year ago
Determine the written description of the complement of the given event. When 13 computers are shipped​, at least one of them is
julsineya [31]

Answer:

A. None of them are defective

True that's equivalent since none defective means 0 defective

Step-by-step explanation:

For this case we have a total of 13 computers and we define the event:

E= "At least one of them is defective"

When we say at last one means that can be 1,2,3,4,5,6,7,8,9,10,11,12 or 13

The complement for this case is E' ="None of them is defective"

Let's analyze one by one the possible options:

A. None of them are defective

True that's equivalent since none defective means 0 defective

B. None of them are free of defects

False thats note equivalent since that means all have defects and that's not the complement.

C. More than one of them are free of defects

False we are interested on the complement and on this case 1 or more defective is not the complement for this case.

D. All of them are defective

False the complement is defined as non of them defective and for this case is not the correct way.

6 0
3 years ago
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