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3 years ago

Choose the correct answer.

Mathematics

1 answer:

Yuri [45]3 years ago

6 0

Step-by-step explanation:

Distance between Train 1 and Train 2=95 miles

Avg speed Train 1 = 45mph, avg speed Train 2=60mph

If both trains leave at the same time and travel toward each other but on parallel tracks, in how much time will their engines be opposite each other?

Let t = travel time (in hrs) until they are opposite each other

Like the hint said, when this happens the total distance traveled by both trains will be 95 mi.

write a distance equation from this fact: Dist = speed * time

;

Train 1 dist + train 2 dist = 95 mi

45t + 60t = 95

105t = 95

t = 95%2F105

t = .90476 hrs

.90476 * 60 = 54.3 min

Check solution by finding the total of the distances the two train travel

45(.90476) + 60(.90476) =

40.7 + 54.3 = 95 mi

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Find the volume of the solid generated by revolving the region bounded by

Rama09 [41]

Answer:

$V =\dfrac{25\pi}{\sqrt{2}}$

Step-by-step explanation:

given,

y=5√sinx

Volume of the solid by revolving

$V = \int_a^b(\pi y^2)dx$

a and b are the limits of the integrals

now,

$V = \int_a^b(\pi (5\sqrt{sinx})^2)dx$

$V =25\pi \int_{\pi/4}^{\pi/2}sinxdx$

$\int sin x = - cos x$

$V =25\pi [-cos x]_{\pi/4}^{\pi/2}$

$V =25\pi [-cos (\pi/2)+cos(\pi/4)]$

$V =25\pi [0+\dfrac{1}{\sqrt{2}}]$

$V =\dfrac{25\pi}{\sqrt{2}}$

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3 years ago

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satela [25.4K]

It is B because tangent lines are always perpendicular to radii

4 0

3 years ago

Read 2 more answers

HELP I DONT GET THIS AT ALL. ITS ABOUT INEQUALITIES EXPLANATION NEEDED

wel

Answer:

Since the slope of the line is (31/4 - 25/4) / (5/4 - 3/4) = 3 that means that for every 1 that x increases, y increases by 3 so an example could be 1 3/4 for x and 9 1/4 for y.

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3 years ago

A 24 foot flagpole casts a 20 foot shadow of the building next to it is an 85 foot shadow find the height of the building

Zigmanuir [339]

Answer: 102 foot / feet tall

Step-by-step explanation:

First, we have to find the unit rate . . . what is 24 divided by 20 ? 1.2/1

Second, multiply . . . what is 1.2 x 85 ? 102

( sorry if this is wrong - I forgot how to do the second part for a sec )

6 0

3 years ago

Let the number of chocolate chips in a certain type of cookie have a Poisson distribution. We want the probability that a cookie

ludmilkaskok [199]

Answer:

$\lambda \geq 6.63835$

Step-by-step explanation:

The Poisson Distribution is "a discrete probability distribution that expresses the probability of a given number of events occurring in a fixed interval of time or space if these events occur with a known constant mean rate and independently of the time since the last event".

Let X the random variable that represent the number of chocolate chips in a certain type of cookie. We know that $X \sim Poisson(\lambda)$

The probability mass function for the random variable is given by:

$f(x)=\frac{e^{-\lambda} \lambda^x}{x!} , x=0,1,2,3,4,...$

And f(x)=0 for other case.

For this distribution the expected value is the same parameter $\lambda$

$E(X)=\mu =\lambda$

On this case we are interested on the probability of having at least two chocolate chips, and using the complement rule we have this:

$P(X\geq 2)=1-P(X$

Using the pmf we can find the individual probabilities like this:

$P(X=0)=\frac{e^{-\lambda} \lambda^0}{0!}=e^{-\lambda}$

$P(X=1)=\frac{e^{-\lambda} \lambda^1}{1!}=\lambda e^{-\lambda}$

And replacing we have this:

$P(X\geq 2)=1-[P(X=0)+P(X=1)]=1-[e^{-\lambda} +\lambda e^{-\lambda}[]$

$P(X\geq 2)=1-e^{-\lambda}(1+\lambda)$

And we want this probability that at least of 99%, so we can set upt the following inequality:

$P(X\geq 2)=1-e^{-\lambda}(1+\lambda)\geq 0.99$

And now we can solve for $\lambda$

$0.01 \geq e^{-\lambda}(1+\lambda)$

Applying natural log on both sides we have:

$ln(0.01) \geq ln(e^{-\lambda}+ln(1+\lambda)$

$ln(0.01) \geq -\lambda+ln(1+\lambda)$

$\lambda-ln(1+\lambda)+ln(0.01) \geq 0$

Thats a no linear equation but if we use a numerical method like the Newthon raphson Method or the Jacobi method we find a good point of estimate for the solution.

Using the Newthon Raphson method, we apply this formula:

$x_{n+1}=x_n -\frac{f(x_n)}{f'(x_n)}$

Where :

$f(x_n)=\lambda -ln(1+\lambda)+ln(0.01)$

$f'(x_n)=1-\frac{1}{1+\lambda}$

Iterating as shown on the figure attached we find a final solution given by:

$\lambda \geq 6.63835$

4 0

3 years ago