Simplify the expression<br><br> (x^2 + 2x + 3)(x^2 – 2x

In 2009, the American Time Use Survey found that the average American spends 2.8 hours a day watching TV. Suppose the standard d

Anit [1.1K]

Answer:

4.72 hours/day

Step-by-step explanation:

Mean time spent watching TV (μ) = 2.8 hours a day

Standard deviation (σ) = 1.5 hours a day

The 90th percentile (upper 10%) of a normal distribution has an equivalent z-score of roughly z = 1.282. The minimum time spent watching TV, X, at the 90th percentile is:

$z=\frac{X-\mu}{\sigma} \\1.282=\frac{X-2.8}{1.5}\\ X=4.72\ hours/day$

On a typical day, you must watch at least 4.72 hours of TV to be in the upper 10%.

8 0

3 years ago

Consider the two lines l1:x=−2t,y=1+2t,z=3tl1:x=−2t,y=1+2t,z=3t and l2:x=−8+4s,y=0+5s,z=5+1sl2:x=−8+4s,y=0+5s,z=5+1s find the po

seraphim [82]

At the point of intersection, the coordinates are the same:

... (x, y, z) = (-2t, 1+2t, 3t) = (-8+4s, 5s, 5+s)

We only need two of the coordinates to solve for the values of s and t. Using the x- and y-coordinates, we have

... 4s + 2t = 8 . . . . . . x2 - x1 = 0, in standard form

... 5s -2t = 1 . . . . . . . y2 - y1 = 0, in standard form

Adding these equations gives 9s=9, so s=1. Substituting into either equation gives t=2.

Using the expression for l1 with t=2, the point of intersection is

... (-2·2, 1+2·2, 3·2) = (-4, 5, 6).

_____

We could have stopped after finding the value of s, because that defines the point. By finding the value of t, we can check the solution to make sure that l1 and l2 both give the same point for the respective values of s and t. (They do.)

8 0

3 years ago

A simple random sample of size nequals81 is obtained from a population with mu equals 83 and sigma equals 27. (a) Describe the

Ivanshal [37]

Answer:

a) $\bar X \sim N (\mu, \frac{\sigma}{\sqrt{n}})$

With:

$\mu_{\bar X}= 83$

$\sigma_{\bar X}=\frac{27}{\sqrt{81}}= 3$

b) $z= \frac{89-83}{\frac{27}{\sqrt{81}}}= 2$

$P(Z>2) = 1-P(Z$

c) $z= \frac{75.65-83}{\frac{27}{\sqrt{81}}}= -2.45$

$P(Z$

d) $z= \frac{89.3-83}{\frac{27}{\sqrt{81}}}= 2.1$

$z= \frac{79.4-83}{\frac{27}{\sqrt{81}}}= -1.2$

$P(-1.2$

Step-by-step explanation:

For this case we know the following propoertis for the random variable X

$\mu = 83, \sigma = 27$

We select a sample size of n = 81

Part a

Since the sample size is large enough we can use the central limit distribution and the distribution for the sampel mean on this case would be:

$\bar X \sim N (\mu, \frac{\sigma}{\sqrt{n}})$

With:

$\mu_{\bar X}= 83$

$\sigma_{\bar X}=\frac{27}{\sqrt{81}}= 3$

Part b

We want this probability:

$P(\bar X>89)$

We can use the z score formula given by:

$z = \frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n}}}$

And if we find the z score for 89 we got:

$z= \frac{89-83}{\frac{27}{\sqrt{81}}}= 2$

$P(Z>2) = 1-P(Z$

Part c

$P(\bar X$

We can use the z score formula given by:

$z = \frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n}}}$

And if we find the z score for 75.65 we got:

$z= \frac{75.65-83}{\frac{27}{\sqrt{81}}}= -2.45$

$P(Z$

Part d

We want this probability:

$P(79.4 < \bar X < 89.3)$

We find the z scores:

$z= \frac{89.3-83}{\frac{27}{\sqrt{81}}}= 2.1$

$z= \frac{79.4-83}{\frac{27}{\sqrt{81}}}= -1.2$

$P(-1.2$

8 0

3 years ago

The original price of a 2018 Honda Shadow to the dealer is $17,715, but the dealer will pay only $16,985 after rebate. If the de

vitfil [10]

Answer:

The final price to be paid after the 2% discount has been made will be $ 16,645.30.

Step-by-step explanation:

Since there is a 2% discount on the price of the Honda Shadow in the event that the dealer pays Honda within 15 days, and that after a rebate the price of the vehicle is $ 16,985, to obtain the value of the discount and the final amount to be paid must be calculated as follows:

16,985 x 2/100 = X

33,970 / 100 = X

339.70 = X

Thus, the discount to be made will be $ 339.70, with which the final price to be paid after the 2% discount has been made will be $ 16,645.30.

4 0

3 years ago

The complement of an angle is three times the measurement of the angle. Find the measurement of the larger angle.

olganol [36]

We know that two complements add up to 90.
Let's call the smaller angle x and the larger y.
3x = y
x + y = 90
We can use simple substitution.
x + 3x = 90
4x = 90
x = 22.5

Then, since we know that 3x=y, we can find the larger angle.
3*22.5 = 67.5

4 0

3 years ago

Simplify the expression (x^2 + 2x + 3)(x^2 – 2x – 2)