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2 years ago

I need help 9th grade math

Mathematics

1 answer:

alexira [117]2 years ago

3 0

hope helps with the first the rest i cant read its not clear.

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Are the two triangles similar? If so, why are they similar?

babunello [35]

The answer is
1. B
2. B

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2 years ago

The graph h = −16t^2 + 25t + 5 models the height and time of a ball that was thrown off of a building where h is the height in f

Thepotemich [5.8K]

Answer:

part 1) 0.78 seconds

part 2) 1.74 seconds

Step-by-step explanation:

step 1

At about what time did the ball reach the maximum?

Let

h ----> the height of a ball in feet

t ---> the time in seconds

we have

$h(t)=-16t^{2}+25t+5$

This is a vertical parabola open downward (the leading coefficient is negative)

The vertex represent a maximum

The x-coordinate of the vertex represent the time when the ball reach the maximum

Find the vertex

Convert the equation in vertex form

Factor -16

$h(t)=-16(t^{2}-\frac{25}{16}t)+5$

Complete the square

$h(t)=-16(t^{2}-\frac{25}{16}t+\frac{625}{1,024})+5+\frac{625}{64}$

$h(t)=-16(t^{2}-\frac{25}{16}t+\frac{625}{1,024})+\frac{945}{64}\\h(t)=-16(t^{2}-\frac{25}{16}t+\frac{625}{1,024})+\frac{945}{64}$

Rewrite as perfect squares

$h(t)=-16(t-\frac{25}{32})^{2}+\frac{945}{64}$

The vertex is the point $(\frac{25}{32},\frac{945}{64})$

therefore

The time when the ball reach the maximum is 25/32 sec or 0.78 sec

step 2

At about what time did the ball reach the minimum?

we know that

The ball reach the minimum when the the ball reach the ground (h=0)

For h=0

$0=-16(t-\frac{25}{32})^{2}+\frac{945}{64}$

$16(t-\frac{25}{32})^{2}=\frac{945}{64}$

$(t-\frac{25}{32})^{2}=\frac{945}{1,024}$

square root both sides

$(t-\frac{25}{32})=\pm\frac{\sqrt{945}}{32}$

$t=\pm\frac{\sqrt{945}}{32}+\frac{25}{32}$

the positive value is

$t=\frac{\sqrt{945}}{32}+\frac{25}{32}=1.74\ sec$

8 0

2 years ago

A set of data items is normally distributed with a mean of 400 and a standard deviation of 60. Find the data item in this distri

Softa [21]

Answer:

The data item is $X = 580$

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 400 and a standard deviation of 60.

This means that $\mu = 400, \sigma = 60$

z=3

We have to find X when Z = 3. So

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

$3 = \frac{X - 400}{60}$

$X - 400 = 3*60$

$X = 580$

The data item is $X = 580$

6 0

2 years ago

PLZZZZ ZHELLL I NEED IT PLZZZZZ

bagirrra123 [75]

Equation:

1.37 + m =7.9

Step by step:

1.37 + m =7.9

-1.37 -1.37

m =6.53

Check Your Answer:

1.37 + 6.53 =7.9

7.9 =7.9

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3 years ago

What is 4 and square root of 72

Katarina [22]

Answer:

square root of 72 is approximately 8.49

i hope that right!

Step-by-step explanation:

8 0

2 years ago