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DochEvi [55]
3 years ago
5

In a smoking survey among boys between the ages of 12 and 17, 78% prefer to date nonsmokers, 1% prefer to date smokers, and 21%

don’t care. Suppose seven such boys are selected randomly. Let X equal the number who prefer to date nonsmokers and Y equal the number who prefer to date smokers. (a) Determine the joint pmf of X and Y. Be sure to include the support of the pmf. (b) Find the marginal pmf of X. Again include the support.
Mathematics
1 answer:
Ganezh [65]3 years ago
4 0

Answer:

i think it is a

Step-by-step explanation:

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What is the following product? (2 square root 7+3 square root 6)(5 square root 2+4 square root 3)
Xelga [282]

(2\sqrt7+3\sqrt6)(5\sqrt2+4\sqrt3)\qquad\text{use distributive property}\\\\=(2\sqrt7)(5\sqrt2)+(2\sqrt7)(4\sqrt3)+(3\sqrt6)(5\sqrt2)+(3\sqrt6)(4\sqrt3)\\\\=10\sqrt{14}+8\sqrt{21}+15\sqrt{12}+12\sqrt{18}\\\\=10\sqrt{14}+8\sqrt{21}+15\sqrt{4\cdot3}+12\sqrt{9\cdot2}\\\\=10\sqrt{14}+8\sqrt{21}+15\sqrt4\cdot\sqrt3+12\sqrt9\cdot\sqrt2\\\\=10\sqrt{14}+8\sqrt{21}+(15)(2)\sqrt3+(12)(3)\sqrt2\\\\=\boxed{10\sqrt{14}+8\sqrt{21}+30\sqrt3+36\sqrt2}

5 0
3 years ago
Read 2 more answers
Without dividing or listing multiples how can you tell if 61 is a multiple of 6.
Ostrovityanka [42]
For a number to be a multiple of 6, it must be divisible by 6
and a number divisble by 6 means that it is divisble by 2 and 3

since the ones digit is odd it is not divisble by 2 which means 61 is not a multiple of 6
7 0
3 years ago
Grading managers. Some companies "grade on a bell curve" to compare the performance of their managers and professional workers.
Monica [59]

Answer:

\mu = 250, \sigma = 175.781

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

X \sim N(\mu,\sigma)  

For this case we have two conditions given:

P(X

P(X>475) = 0.1 or equivalently P(X

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}

So we can find a value from the normal standard distribution that accumulates 0.1 and 0.9 of the area in the left, for this case the two values are:

z= -1.28, z=-1.28

We can verify that P(Z<-1.28) =0.1[/tex] and P(Z<1.28) =0.9[/tex]

And then using the z score we have the following formulas:

-1.28 = \frac{25 -\mu}{\sigma}   (1)

1.28 = \frac{475 -\mu}{\sigma}   (2)

If we add equations (1) and (2) we got:

\frac{25 -\mu}{\sigma} + \frac{475 -\mu}{\sigma} =0

We can multiply both sides of the equation by \sigma and we got:

25+ 475 -2 \mu = 0

\mu = \frac{500}{2}= 250

And then we can find the standard deviation for example from equation (1) and we got:

\sigma = \frac{25-250}{-1.28}=175.781

So then the answer would be:

\mu = 250, \sigma = 175.781

 

3 0
3 years ago
I just need to check if I'm right. For 9 and 10
Arlecino [84]
9 and 10 are correct :)
5 0
3 years ago
HELP!!!
ki77a [65]
Length of the outer frame: 4+2x
width of the outer frame: 3+2x
area of the outframe: (4+2x)(3+2x)=15
expand the equation: 12+8x+6x+12x^2=15
combine like terms: 4x^2+14x-3=0
4 0
3 years ago
Read 2 more answers
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