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blagie [28]
3 years ago
8

A professor uses a video camera to record the motion of an object falling from a height of 250 meters. The function f(x) = –5x2

+ 250 can be used to represent the approximate height of the object off the ground after x seconds. Which is the best estimate for the amount of time elapsed when the object is 120 meters off the ground?
4 seconds
5 seconds
6 seconds
7 seconds
Mathematics
2 answers:
Romashka [77]3 years ago
8 0

Answer:

The answer is approximately 5.09 seconds.

Step-by-step explanation:

The given equation is:

f(x) = -5x^2 + 250

To find the elapsed time, x, set the equation equal to 120 and solve for x:

-5x^2 + 250 = 120

-5x^2 = -130

x^2 = -130/-5 = 26

x = Sqrt(26) = 5.09 seconds.

e-lub [12.9K]3 years ago
3 0

Answer:

B

Step-by-step explanation:

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Answer:

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Step-by-step explanation:

Scores are normally distributed with a mean of 460 and a standard deviation of 80. For a value x, the associated z-score is computed as z = \frac{x-460}{80}, therefore, the z-score for 400 is given by z_{0} = (400-460)/80 = -0.75. To compute the fraction of the applicants that we would expect to have a score of 400 or above, we should compute the probability P(Z > -0.75) = 0.7734, i.e., the fraction or percentage of the applicants that we would expect to have a score of 400 or above is 77.34%

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Answer:

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Answer:

m=\frac{S_{xy}}{S_{xx}}  

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S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}{n}  

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On this case the correct answer would be:

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Step-by-step explanation:

Assuming the following options:

A.  there is a positive correlation between X and Y

B.  there is a negative correlation between X and Y

C.  if X is increased, Y must also increase

D.  if Y is increased, X must also increase

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If we want a model y = mx +b where m represent the lope and b the intercept

m=\frac{S_{xy}}{S_{xx}}  

Where:  

S_{xy}=\sum_{i=1}^n x_i y_i -\frac{(\sum_{i=1}^n x_i)(\sum_{i=1}^n y_i)}{n}  

S_{xx}=\sum_{i=1}^n x^2_i -\frac{(\sum_{i=1}^n x_i)^2}{n}  

\bar x= \frac{\sum x_i}{n}  

\bar y= \frac{\sum y_i}{n}  

And we can find the intercept using this:  

b=\bar y -m \bar x  

On this case the correct answer would be:

E.  none of the above

Since the intercept has no association between the increase/decrease of the dependent variable respect to the independent variable

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3 years ago
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