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2 years ago

I really need help with these 3 questions plsss

Mathematics

1 answer:

DIA [1.3K]2 years ago

5 0

#3.

Let's first make an equation out of the information given about Frank: y = -15x + 630.

Then, we can plug in 20 for x to find out how many bricks he has after 20 minutes.

-15(20) + 630 = 330

So, Frank has 330 bricks left after 20 minutes. If we look at the graph, find 20 minutes on the x-axis, and follow that up to where it meets with the line, we can see that Francis has only 320 bricks remaining after 20 minutes.

Therefore, Francis will have the fewest bricks left after 20 minutes.

#2.

First, we need a bit of information about both of the functions: the slope and y-intercept. The slope of function W is 1/2, and the y-intercept is -1. The slope of function Z is 1/4, and the y-intercept is -2. Now, let's take a look at the options.

1. False - 1/2 is greater than 1/4

2. True - 1/2 is greater than 1/4

3. False - -2 does not equal -1

4. False - -1 is greater than -2 (closer to 0)

5 & 6. False - The y-value when you plug -4 into function W is -3, and the y-value when you plug -4 into function Z is also -3.

#1.

This problem involves using the slope formula for functions A and B, and finding m in the equation for function C.

Slope of function A = 2

Slope of function B = 3/5

Slope of function C = 3

Therefore, in order from least to greatest is: B, A, C.

Hope this helps!! :)

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3 years ago

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3 years ago

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Answer:

$z=-1.28$

And if we solve for a we got

$a=470 -1.28*60=393.2$

So the value of height that separates the bottom 10% (Fastest 10%) of data from the top 90% is 393.2.

so if the time is 393.2 or lower a boy would earn a certificate of recognition from the fitness association

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".

Solution to the problem

Let X the random variable that represent the time for this event of a population, and for this case we know the distribution for X is given by:

$X \sim N(470,60)$

Where $\mu=470$ and $\sigma=60$

NOTE: For this case the fastest 10% is on the lower tail of the distribution

For this part we want to find a value a, such that we satisfy this condition:

$P(X>a)=0.9$ (a)

$P(X$ (b)

Both conditions are equivalent on this case. We can use the z score again in order to find the value a.

As we can see on the figure attached the z value that satisfy the condition with 0.1 of the area on the left and 0.9 of the area on the right it's z=-1.28. On this case P(Z<-1.28)=0.1 and P(z>-1.28)=0.9

If we use condition (b) from previous we have this:

$P(X$

$P(z$

But we know which value of z satisfy the previous equation so then we can do this:

$z=-1.28$

And if we solve for a we got

$a=470 -1.28*60=393.2$

So the value of height that separates the bottom 10% (Fastest 10%) of data from the top 90% is 393.2.

so if the time is 393.2 or lower a boy would earn a certificate of recognition from the fitness association

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