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castortr0y [4]
3 years ago
13

You have a 20% off coupon to use at the store. Your total was $80 before the discount. H

Mathematics
1 answer:
12345 [234]3 years ago
4 0

Answer:

C) $64

Step-by-step explanation:

(80 x 20)/100 = $16.00

Final Price:

80 - 16.00 = $64.00

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X–2 1/2=6 3/4. X=?<br><br> x – 3.23 = 0.77. X=?
Over [174]

Answer:

x= 105/4

x=4

Step-by-step explanation:

5 0
3 years ago
Read 2 more answers
A ball is projected in to the air. Its height at time t is given by the equation
Ksju [112]
The equation gives the height of the ball. That is, h is the height of the ball. t is the time. Since we are looking for the time at which the height is 8 (h=8), we need to set the equation equal to 8 and solve for t. We do this as follows:

h=-16 t^{2} +60t+1
8=-16 t^{2} +60t+1
16 t^{2} -60t-1+8=0
16 t^{2} -60t+7=0

This is a quadratic equation and as it is set equal to 0 we can solve it using the quadratic formula. That formula is:
t= \frac{-bplus minus \sqrt{ b^{2}-4ac } }{2a}
You might recall seeing this as "x=..." but since our equation is in terms of t we use "t-=..."

In order to use the formula we need to identify a, b and c.
a = the coefficient (number in front of) t^{2} = 16.
b = the coefficient of t = -60
c = the constant (the number that is by itself) = 7

Substituting these into the quadratic formula gives us:
t= \frac{-(-60)plus minus \sqrt{ (-60)^{2}-4(16)(7) } }{2(16)}
t= \frac{60plus minus \sqrt{3600-448 } }{32}
t= \frac{60plus minus \sqrt{3152 } }{32}

As we have "plus minus" (this is usually written in symbols with a plus sign over a minus sign) we split the equation in two and obtain:
t=  \frac{60+56.1426}{32} =3.63
and
t=  \frac{60-56.1426}{32} =.12

So the height is 8 feet at t = 3.63 and t=.12

It should make sense that there are two times. The ball goes up, reaches it's highest height and then comes back down. As such the height will be 8 at some point on the way up and also at some point on the way down.


3 0
3 years ago
Terri Vogel, an amateur motorcycle racer, averages 129.71 seconds per 2.5 mile lap (in a 7 lap race) with a standard deviation o
Vikki [24]

Answer:

(a) The percent of her laps that are completed in less than 130 seconds is 55%.

(b) The fastest 3% of her laps are under 125.42 seconds.

(c) The middle 80% of her laps are from <u>126.80</u> seconds to <u>132.63</u> seconds.

Step-by-step explanation:

The random variable <em>X</em> is defined as the number of seconds for a randomly selected lap.

The random variable <em>X </em>is normally distributed with mean, <em>μ</em> = 129.71 seconds and standard deviation, <em>σ</em> = 2.28 seconds.

Thus, X\sim N(129.71,\ 2.28^{2}).

(a)

Compute the probability that a lap is completes in less than 130 seconds as follows:

P(X

                   =P(Z

The percentage is, 0.55 × 100 = 55%.

Thus, the percent of her laps that are completed in less than 130 seconds is 55%.

(b)

Let <em>x</em> represents the 3rd percentile.

That is, P (X < x) = 0.03.

⇒ P (Z < z) = 0.03

The value of <em>z</em> for the above probability is:

<em>z</em> = -1.88

Compute the value of <em>x</em> as follows:

z=\frac{x-\mu}{\sigma}\\-1.88=\frac{x-129.71}{2.28}\\x=129.71-(1.88\times 2.28)\\x=125.4236\\x\approx 125.42

Thus, the fastest 3% of her laps are under 125.42 seconds.

(c)

Let <em>x</em>₁ and <em>x</em>₂ be the values between which the middle 80% of the distribution lie.

That is,

P(x_{1}

The value of <em>z</em> for the above probability is:

<em>z</em> = 1.28

Compute the values of <em>x</em>₁ and <em>x</em>₂ as follows:

-z=\frac{x_{1}-\mu}{\sigma}\\-1.28=\frac{x_{1}-129.71}{2.28}\\x_{1}=129.71-(1.28\times 2.28)\\x=126.7916\\x\approx 126.80               z=\frac{x_{2}-\mu}{\sigma}\\1.28=\frac{x_{2}-129.71}{2.28}\\x_{2}=129.71+(1.28\times 2.28)\\x=132.6284\\x\approx 132.63

Thus, the middle 80% of her laps are from <u>126.80</u> seconds to <u>132.63</u> seconds.

5 0
3 years ago
Calculate this reflection of the triangle:
Mice21 [21]

Answer:

a = 3, b = 0, c = 0, d = -2

Step-by-step explanation:

<em>To find the reflection Multiply the matrices</em>

∵ The dimension of the first matrix is 2 × 2

∵ The dimension of the second matrix is 2 × 3

<em>1. Multiply the first row of the 1st matrix by each column in the second matrix add the products of each column to get the first row in the 3rd matrix.</em>

2. Multiply the second row of the 1st matrix by each column in the second matrix add the products of each column to get the second row of the 3rd matrix

\left[\begin{array}{ccc}1&0\\0&-1\end{array}\right]  × \left[\begin{array}{ccc}0&3&0\\0&0&2\end{array}\right]  = \left[\begin{array}{ccc}(1*0+0*0)&(1*3+0*0)&(1*0+0*2)\\(0*0+-1*0)&(0*3+-1*0)&(0*0+-1*2)\end{array}\right]=\left[\begin{array}{ccc}0&3&0\\0&0&-2\end{array}\right]

Compare the elements in the answer with the third matrix to find the values of a, b, c, and d

∴ a = 3

∴ b = 0

∴ c = 0

∴ d = -2

7 0
4 years ago
Solve $16x+9=9y-2x$ for $y$ .
s344n2d4d5 [400]

Answer:

The solution for y is y = 2x + 1

Step-by-step explanation:

* <em>Lets explain how to solve an equation for one of the variables</em>

- We need to solve the equation 16x + 9 = 9y - 2 x for y

- That means we want to find y in terms of x and the numerical term

- the equation has two sides, one side contains x and numerical term

 and the other side contains y and x

- We need to separate y in one side, and other term in the other side

* <em>Lets do that</em>

∵ 16x + 9 = 9y - 2x

- Add 2x to both sides to cancel -2x from the right side

∴ 16x + 2x + 9 = 9y - 2x + 2x

- Add like terms in each side

∴ 18x + 9 = 9y

- Divide each term by the coefficient of y ⇒ (÷9)

∴ (18 ÷ 9)x + (9 ÷ 9) = (9 ÷ 9)y

∴ 2x + 1 = y

- Switch the two sides

∴ y = 2x + 1

* The solution for y is y = 2x + 1

3 0
3 years ago
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