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2 years ago

5

Jenifer is flying her kite and it gets stuck in a tree. She knows the string on her kite is 25 feet long and she is 12 feet from

the tree.
How long of a ladder (in feet) will she need to get her kite out of the tree?

1 answer:

uysha [10]2 years ago

8 0

Answer:

13

Step-by-step explanation:

25 - 12 = 13

I think this is what you're asking, I don't know.

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Glenn needs 20 minutes to clean his room. If his little sister Veronika pulls things out while he is cleaning, it takes 60 minut

Bogdan [553]

Answer:

It takes 30 minutes

Step By Step:

The rate of Glenn in finishing a job would be equivalent to:

Rate (G) = 1

job / 20 minutes

While the rate of Veronika is:

Rate (V) = 1

job / x---> x is the unknown

Where 1 job for Glenn means completely cleaning his room while 1 job for Veronika means pulling out everything. Therefore the equation to use would be:

1 / 20 – 1 /

x = 1 / 60

The rate of

Veronika is subtracted from the rate of Glenn since Veronika is slowing Glenn

down. Solving for x:

Multiply both

sides by 60 x

(1 / 20 – 1 /

x = 1 / 60) * 60 x

3 x – 60 = x

2 x = 60

x = 30

Therefore it

takes 30 minutes for Veronika to pull everything out.

3 0

3 years ago

Our faucet is broken, and a plumber has been called. The arrival time of the plumber is uniformly distributed between 1pm and 7p

Ymorist [56]

Answer:

$E(A+B) = E(A)+E(B)=4+0.5 =4.5 hours$

$Var(A+B)= Var(A)+Var(B)=3+0.25 hours^2=3.25 hours^2$

Step-by-step explanation:

Let A the random variable that represent "The arrival time of the plumber ". And we know that the distribution of A is given by:

$A\sim Uniform(1 ,7)$

And let B the random variable that represent "The time required to fix the broken faucet". And we know the distribution of B, given by:

$B\sim Exp(\lambda=\frac{1}{30 min})$

Supposing that the two times are independent, find the expected value and the variance of the time at which the plumber completes the project.

So we are interested on the expected value of A+B, like this

$E(A +B)$

Since the two random variables are assumed independent, then we have this

$E(A+B) = E(A)+E(B)$

So we can find the individual expected values for each distribution and then we can add it.

For ths uniform distribution the expected value is given by $E(X) =\frac{a+b}{2}$ where X is the random variable, and a,b represent the limits for the distribution. If we apply this for our case we got:

$E(A)=\frac{1+7}{2}=4 hours$

The expected value for the exponential distirbution is given by :

$E(X)= \int_{0}^\infty x \lambda e^{-\lambda x} dx$

If we use the substitution $y=\lambda x$ we have this:

$E(X)=\frac{1}{\lambda} \int_{0}^\infty y e^{-\lambda y} dy =\frac{1}{\lambda}$

Where X represent the random variable and $\lambda$ the parameter. If we apply this formula to our case we got:

$E(B) =\frac{1}{\lambda}=\frac{1}{\frac{1}{30}}=30min$

We can convert this into hours and we got E(B) =0.5 hours, and then we can find:

$E(A+B) = E(A)+E(B)=4+0.5 =4.5 hours$

And in order to find the variance for the random variable A+B we can find the individual variances:

$Var(A)= \frac{(b-a)^2}{12}=\frac{(7-1)^2}{12}=3 hours^2$

$Var(B) =\frac{1}{\lambda^2}=\frac{1}{(\frac{1}{30})^2}=900 min^2 x\frac{1hr^2}{3600 min^2}=0.25 hours^2$

We have the following property:

$Var(X+Y)= Var(X)+Var(Y) +2 Cov(X,Y)$

Since we have independnet variable the Cov(A,B)=0, so then:

$Var(A+B)= Var(A)+Var(B)=3+0.25 hours^2=3.25 hours^2$

3 0

3 years ago

I need to know how to do it in Distributive Property.

kotykmax [81]

A(b-c)=ab-ac

(1/7)(1/3h-1/2)=(1/7)(1/3h)-(1/7)(1/2)=1/21h-1/14

now we gots
6 and 1/7+1/21h-1/14
rearange
6 and 1/7-1/14+1/21h
make common denom which is 14
6 and 2/14-1/14+1/21h
6 and 1/14+1/21h

6 0

3 years ago

X+5 divided by 3=15 what is the answer?

GREYUIT [131]

All you have to do is solve for x. See the following steps below.

Step 1. Subtract $\frac{5}{3}$ from both sides

$X= 15-\frac{5}{3}$

Step 2. Simplify $15- \frac{3}{5}$ to $\frac{40}{3}$

$X= \frac{40}{3}$

4 0

3 years ago

Read 2 more answers

Find, explain, and correct the error in the student work below.

Artemon [7]

The correct answer is 0

6 0

3 years ago