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3 years ago

What is the coefficient of x2 in the expansion of (x + 2)3?

1 answer:

4 0

One way is that you can just factor it out: (x+2)(x+2)(x+2)
For the first pair, you get $x^2+4x+4$ .
Then do $(x^2+4x+4)$ * $(x+2)$
That will be $x^3+6x^2+12x+8$
So the answer is 6

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7. A number of minor automobile accidents occur at various high-risk intersections in Teton County despite traffic lights. The T

Anit [1.1K]

Answer:

Modification has not reduced the number of accidents.

Step-by-step explanation:

$H_0: \mu\geq0\\H_a:\mu$

A B C D E F G H

Before modification 5 7 6 4 8 9 8 10

After modification 3 7 7 0 4 6 8 2

Difference -2 0 1 -4 -4 -3 0 -8

Mean of differences $M_d = \frac{sum}{8}=\frac{2+0-1+4+4+3-0+8}{8}=2.5$

Standard deviation of differences = $\sqrt{\frac{\sum(x-\bar{x})^2}{n}}=2.9277$

Formula of paired t test :

$t=\frac{M_d}{\frac{s}{\sqrt{n}}}\\t=\frac{2.5}{\frac{2.9277}{\sqrt{8}}}\\t = 2.4152$

Df = n-1 = 8-1 =7

$t critical = t_{(df, \alpha)}=t_{7,0.01}=2.998$

t critical> t calculated

So, We failed to reject null hypothesis

Hence modification has not reduced the number of accidents.

6 0

3 years ago

A jar contains 4 white and 4 black marbles. We randomly choose 4 marbles. If 2 of them are white and 2 are black, we stop. If no

Airida [17]

Answer:

<em>Find the probability of success in a single trial and then think about the nature of the problem (when do we stop). </em>

Step-by-step explanation:

Observe that in the single trial, we have (8 4) possibilities of choosing our set of balls. If we have chosen two white balls and two black balls, the probability of doing that is simply

p=(4 2)*(4 2)/(8 4)

This is well know Hyper geometric distribution. Now, define random variable X that marks the number of trials that have been needed to obtain the right combination (two white and two black balls). From the nature of the problem, observe that X has Geometric distribution with parameter p that has been calculated above. Hence

P(X = n) = (1— p)^n-1 *( p )

<em>Find the probability of success in a single trial and then think about the nature of the problem (when do we stop). </em>

3 0

3 years ago

It costs $3.55 to make a sandwich at the local deli shop. To make a profit, the deli sells it at a price that is 160% of the cos

larisa [96]

Okay this is what i got it might be wrong but i did it and then looked it up to make sure i was right & it showed the same answer!!

3.55 * 1.6= 5.68!!

4 0

3 years ago

Read 2 more answers

How do you solve -2/3(12c-9)+14c

Oliga [24]

You can't solve it, but you can simplify it
-2/3 * (12c - 9) + 14c = -2/3*12c - (-2/3)*9 + 14c = -8c + 6 + 14 c = 6c + 6

6 0

3 years ago

The circumference of a circle is 56.52 feet. What is the circle's radius?

matrenka [14]

Answer:

If we substitute pi as 3.14 we would be doing -

56.52/3.14 = 18

18/2 = 9.

So the circle's radius would be 9.

BUT if you want it with PI. . .

The answer would be 8.995437385

7 0

3 years ago