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3 years ago

D.

Mathematics

1 answer:

-Dominant- [34]3 years ago

7 0

Answer:

C and d

Step-by-step explanation:

C and d are similar triangles. I think that’s what you mean. I just did the test

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An auto parts store is examining how many items were purchased per transaction at the store as compared to their online website.

anastassius [24]

Answer:

0.4394

Step-by-step explanation:

given that an auto parts store is examining how many items were purchased per transaction at the store as compared to their online website

The data is shown below:

Frequency Frequency*Midpt

Midpt Online Total Online Total

1-3 2 40 147 80 294

4-6 5 60 103 300 515

7-9 8 15 32 120 256

10-12 11 5 18 55 198

120 300 555 1263

Thus we find total items purchased on line = 555

and total items overall purchased = 1263

Hence the probability that a randomly selected item was purchased online

= $\frac{555}{1263} \\=0.4394$

4 0

3 years ago

Find the mean, variance &a standard deviation of the binomial distribution with the given values of n and p.

MrMuchimi

A random variable following a binomial distribution over $n$ trials with success probability $p$ has PMF

$f_X(x)=\dbinom nxp^x(1-p)^{n-x}$

Because it's a proper probability distribution, you know that the sum of all the probabilities over the distribution's support must be 1, i.e.

$\displaystyle\sum_xf_X(x)=\sum_{x=0}^n\binom nxp^x(1-p)^{n-x}=1$

The mean is given by the expected value of the distribution,

$\mathbb E(X)=\displaystyle\sum_xf_X(x)=\sum_{x=0}^nx\binom nxp^x(1-p)^{n-x}$
$\mathbb E(X)=\displaystyle\sum_{x=1}^nx\frac{n!}{x!(n-x)!}p^x(1-p)^{n-x}$
$\mathbb E(X)=\displaystyle\sum_{x=1}^n\frac{n!}{(x-1)!(n-x)!}p^x(1-p)^{n-x}$
$\mathbb E(X)=\displaystyle np\sum_{x=1}^n\frac{(n-1)!}{(x-1)!((n-1)-(x-1))!}p^{x-1}(1-p)^{(n-1)-(x-1)}$
$\mathbb E(X)=\displaystyle np\sum_{x=0}^n\frac{(n-1)!}{x!((n-1)-x)!}p^x(1-p)^{(n-1)-x}$
$\mathbb E(X)=\displaystyle np\sum_{x=0}^n\binom{n-1}xp^x(1-p)^{(n-1)-x}$
$\mathbb E(X)=\displaystyle np\sum_{x=0}^{n-1}\binom{n-1}xp^x(1-p)^{(n-1)-x}$

The remaining sum has a summand which is the PMF of yet another binomial distribution with $n-1$ trials and the same success probability, so the sum is 1 and you're left with

$\mathbb E(x)=np=126\times0.27=34.02$

You can similarly derive the variance by computing $\mathbb V(X)=\mathbb E(X^2)-\mathbb E(X)^2$ , but I'll leave that as an exercise for you. You would find that $\mathbb V(X)=np(1-p)$ , so the variance here would be

$\mathbb V(X)=125\times0.27\times0.73=24.8346$

The standard deviation is just the square root of the variance, which is

$\sqrt{\mathbb V(X)}=\sqrt{24.3846}\approx4.9834$

7 0

4 years ago

241.78 divided by (-3.85)

koban [17]

Answer:

-62.8 is the answer .......................

3 0

3 years ago

Read 2 more answers

-5(x – 3) = x + 27<br> What’s the answer to this

Leona [35]

-5(x – 3) = x + 27

multiply the bracket by -5

(-5)(x)=-5x

(-5)(-3)=15

-5x+15=x+27

Move +15 to the other side. Sign changes from +15 to -15.

-5x+15-15=x+27-15

-5x=x+27-15

-5x=x+12

Move +x to the other side. Sign changes from +x to -x.

-5x-x=x-x+12

-6x=12

Divide both sides by -6

-6x/-6=12/-6

Answer: x=-2

3 0

3 years ago

Lines

xeze [42]

Answer:

x=27, y=18

Step-by-step explanation:

Angle CB is 128, which means angle AC is 72. We can confirm angle O is also 72, since the lines are straight. Angle AM is 27, because AN is a right angle. 63+72+27= 162 180-162=18 Angle ND is 18.

6 0

4 years ago

Read 2 more answers