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Luden [163]
2 years ago
6

Suppose that diameters of a new species of apple have a bell-shaped distribution with a mean of 7.46cm and a standard deviation

of 0.39cm. Using the empirical rule, what percentage of the apples have diameters that are greater than 7.07cm? Please do not round your answer.
Mathematics
1 answer:
kondaur [170]2 years ago
3 0

Answer:

84% of the apples have diameters that are greater than 7.07cm.

Step-by-step explanation:

The Empirical Rule states that, for a normally distributed random variable:

68% of the measures are within 1 standard deviation of the mean.

95% of the measures are within 2 standard deviation of the mean.

99.7% of the measures are within 3 standard deviations of the mean.

Also, since the normal distribution is symmetric:

50% of measures are above the mean and 50% are below.

Of those 68% within 1 standard deviation of the mean, 34% are between one standard deviation below the mean and the mean, and 34% are between the mean and one standard deviation above the mean.

Of those 95% within 2 standard deviation of the mean, 47.5% are between two standard deviations below the mean and the mean, and 47.5% are between the mean and two standard deviations above the mean.

Of those 99.7% within 3 standard deviation of the mean, 49.85% are between 3 standard deviations below the mean and the mean, and 49.85% are between the mean and 3 standard deviations above the mean.

In this problem, we have that:

Mean = 7.46cm

Standard deviation = 0.39 cm

Using the empirical rule, what percentage of the apples have diameters that are greater than 7.07cm?

7.07 is one standard deviation below the mean.

50% of apples have diameters above the mean, that is, 50% of the apples have diameters above 7.46cm.

34% have diameters between one standard deviation below the mean and the mean, that is, between 7.07cm and 7.46cm.

So 84% of the apples have diameters that are greater than 7.07cm.

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Drew creates a table of ordered pairs representing the width and area of a dog pen. Which situation could describe Drew’s plans
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Step-by-step explanation:


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Grades on a standardized test are known to have a mean of 1000 for students in the United States. The test is administered to 45
vovikov84 [41]

Answer:

a. The 95% confidence interval is 1,022.94559 < μ < 1,003.0544

b. There is significant evidence that Florida students perform differently (higher mean) differently than other students in the United States

c. i. The 95% confidence interval for the change in average test score is; -18.955390 < μ₁ - μ₂ < 6.955390

ii. There are no statistical significant evidence that the prep course helped

d. i. The 95% confidence interval for the change in average test scores is  3.47467 < μ₁ - μ₂ < 14.52533

ii. There is statistically significant evidence that students will perform better on their second attempt after the prep course

iii. An experiment that would quantify the two effects is comparing the result of the confidence interval C.I. of the difference of the means when the student had a prep course and when the students had test taking experience

Step-by-step explanation:

The mean of the standardized test = 1,000

The number of students test to which the test is administered = 453 students

The mean score of the sample of students, \bar{x} = 1013

The standard deviation of the sample, s = 108

a. The 95% confidence interval is given as follows;

CI=\bar{x}\pm z\dfrac{s}{\sqrt{n}}

At 95% confidence level, z = 1.96, therefore, we have;

CI=1013\pm 1.96 \times \dfrac{108}{\sqrt{453}}

Therefore, we have;

1,022.94559 < μ < 1,003.0544

b. From the 95% confidence interval of the mean, there is significant evidence that Florida students perform differently (higher mean) differently than other students in the United States

c. The parameters of the students taking the test are;

The number of students, n = 503

The number of hours preparation the students are given, t = 3 hours

The average test score of the student, \bar{x} = 1019

The number of test scores of the student, s = 95

At 95% confidence level, z = 1.96, therefore, we have;

The confidence interval, C.I., for the difference in mean is given as follows;

C.I. = \left (\bar{x}_{1}- \bar{x}_{2}  \right )\pm z_{\alpha /2}\sqrt{\dfrac{s_{1}^{2}}{n_{1}}+\dfrac{s_{2}^{2}}{n_{2}}}

Therefore, we have;

C.I. = \left (1013- 1019  \right )\pm 1.96 \times \sqrt{\dfrac{108^{2}}{453}+\dfrac{95^{2}}{503}}

Which gives;

-18.955390 < μ₁ - μ₂ < 6.955390

ii. Given that one of the limit is negative while the other is positive, there are no statistical significant evidence that the prep course helped

d. The given parameters are;

The number of students taking the test = The original 453 students

The average change in the test scores, \bar{x}_{1}- \bar{x}_{2} = 9 points

The standard deviation of the change, Δs = 60 points

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C.I. = \bar{x}_{1}- \bar{x}_{2} + 1.96 × Δs/√n

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Xelga [282]

Answer:

Option (3) is correct.

side length of square is (3x + 13 ) units.

Step-by-step explanation:

For a square with side 'a'. Perimeter is defined as the sum of length of side. Since, Square has four sides. Thus Perimeter of square = 4 × side

Given square has perimeter = 12x + 52

Comparing both sides,

4 × side = 12 x +  52

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Thus, side length of square is (3x + 13 ) units.

Thus, option (3) is correct.

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