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3 years ago

12

Michelle flips a penny four times, and it lands heads up all four times. On her fifth flip, what is the probability that the pen

ny will land tails up? Explain.

1 answer:

snow_tiger [21]3 years ago

8 0

Answer:

1/2

Step-by-step explanation:

theoretical probability of a coin flip is always 50% heads, 50% tails

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(12) - (23 +131) =<br> Express your answer in the form (a + bi),

4vir4ik [10]

Answer:

-142

Step-by-step explanation:

First solve parenthesis,

(12) - (23 +131) =

(12) -154

Finally subtract,

12-154

= -142

5 0

3 years ago

PLEASE HELP THIS IS A TIMED QUESTION ON A QUIZ!!!

pantera1 [17]

Answer:

a) 11, d) 25, e) 14, b) 25, c) 28, f) 33

Step-by-step explanation:

<h3>Given</h3>

ΔBDF, with H is the centroid of BDF, DF = 50, CF = 42, and BH = 22

<h3>To find</h3>

HE , DE , CH, EF, HF, BE

<h3>Solution</h3>

As per definition of the centroid, the points C, E and G are midpoints of respective sides and the length of short and long distances from the centroid have ratio of 1/3 and 2/3 of median

a) HE = 1/2BH = 1/2(22) = 11
d) DE = 1/2DF = 1/2(50) = 25
e) CH = 1/3CF = 1/3(42) = 14
b) EF = DE = 25
c) HF = 2/3CF = 2/3(42) = 28
f) BE =BH + HE = 22 + 11 = 33

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

4<br> x 15 =<br> What is the product

Marysya12 [62]

Answer: 60

Step-by-step explanation: multiply four by 15 in this case take four 15's and add them all up

3 0

3 years ago

Read 2 more answers

5: Answer the questions completely: Jordan has a new puppy. She wants to put a fence around part of her yard to cover an area of

irga5000 [103]

Given that Jordan has a new puppy and she wants to put a fence around part of her yard to cover an area of 200 square feet.

Now we have to find what dimensions (length x width) should she make the rectangular area. None of the length or width are given so there can be lots of answers.

Since area is rectangular and we know that rectangle has different value of length and width so we just need to find two factors of given area 200 square feet.

For example 20 times 10 is 200.

So the dimension of the rectangular area will be:

Length = 20 feet and width = 10 feet

Now perimeter of the rectangle is given by formula:

Perimeter = 2(length+width) = 2(20+10)=2(30)=60

Hence perimeter is 60 feet.

8 0

3 years ago