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3 years ago

8.9 – 1.4x + (–6.5x) + 3.4

Mathematics

2 answers:

luda_lava [24]3 years ago

7 0

Answer:

12.3 – 7.9x

Step-by-step explanation:

the product of + and - is -

Therefore,

8.9 – 1.4x + (–6.5x) + 3.4

= 8.9 – 1.4x –6.5x + 3.4

collect like terms

= – 1.4x – 6.5x + 3.4 + 8.9

= –7.9x + 12.3

= 12.3 – 7.9x

Sphinxa [80]3 years ago

3 0

8.9 + 3.4 -1.4x - 6.5x = 12.3 - 7.9x

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Harman [31]

Answer:

Step-by-step explanation:

So, we started out with 2,400 black rhinos.

And we know that they are declining at a rate of 10% per year.

In other words, each subsequent year will only have 90% of the previous year's rhinos.

Therefore, our function is:

$f(x)=2400(.9)^x$

We can do some elimination first.

First, the starting point or y-intercept must be 2400 since that's the number of rhinos we started out with.

Therefore, we can eliminate A and D.

From the remaining choices B or C, we can technically also eliminate B. This is because from our function, we know it's exponential decay, and exponential decay is not a straight line.

However, to double check, let's check the population after 10 years using our function. So:

$f(10)=2400(.9)^{10}$

Use a calculator:

$f(10)\approx837$

So, after 10 years, the population should be around 840.

B is definitely not 840 (at x=10). However, C is right around it.

Therefore, we can conclude that C is the right answer.

And we're done!

6 0

3 years ago

Consider a value to be significantly low if its z score less than or equal to minus−2 or consider a value to be significantly hi

ziro4ka [17]

Answer:

If the weight is higher than 5.8886 gr would be considered significantly high

If the weight is lower than 5.6121 gr would be considered significantly low

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 weights of a population, and for this case we know the distribution for X is given by:

$X \sim N(5.75241,0.06281)$

Where $\mu=5.75241$ and $\sigma=0.06281$

And the best way to solve this problem is using the normal standard distribution and the z score given by:

$z=\frac{x-\mu}{\sigma}$

For the case when z =-2 we can do this:

$-2 = \frac{X-5.75241}{0.06281}$

And if we solve for X we got:

$X = 5.75241 -2*0.06281 =5.6121$

And for the other case when Z=2 we have:

$2 = \frac{X-5.75241}{0.06281}$

And if we solve for X we got:

$X = 5.75241 +2*0.06281 =5.8886$

If the weight is higher than 5.8886 gr would be considered significantly high

If the weight is lower than 5.6121 gr would be considered significantly low

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3 years ago

A rectangular prism has the dimensions 8 feet by 3 feet by 5 feet. What is the surface area of the prism?

raketka [301]

Answer:

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8 0

3 years ago

14w – 2(1 – w) = 2(5w - 1)

joja [24]

Answer:

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Step-by-step explanation:

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3 years ago

A car is being driven at a rate of 40 ft/sec when the brakes are applied. The car decelerates at a constant rate of 10 ft/sec2.

IRISSAK [1]

Answer:

80 feet

Step-by-step explanation:

Given:

Initial speed of the car ( $v_0$ ) = 40 ft/sec

Deceleration of the car ( $\frac{dv}{dt}$ ) = -10 ft/sec²

Final speed of the car ( $v_x$ ) = 0 ft/sec

Let the distance traveled by the car be 'x' at any time 't'. Let 'v' be the velocity at any time 't'.

Now, deceleration means rate of decrease of velocity.

So, $\frac{dv}{dt}=-10\ ft/sec^2$

Negative sign means the velocity is decreasing with time.

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$\frac{dv}{dx}\cdot\frac{dx}{dt}= -10\\\\But\ \frac{dx}{dt}=v.\ So,\\\\v\frac{dv}{dx}=-10\\\\vdv=-10dx$

Integrating both sides under the limit 40 to 0 for 'v' and 0 to 'x' for 'x'. This gives,

$\int\limits^0_{40} {v} \, dv=\int\limits^x_0 {-10} \, dx\\\\\left [ \frac{v^2}{2} \right ]_{40}^{0}=-10x\\\\-10x=\frac{0}{2}-\frac{1600}{2}\\\\10x=800\\\\x=\frac{800}{10}=80\ ft$

Therefore, the car travels a distance of 80 feet before stopping.

4 0

3 years ago