Evaluate this expression. (−36.28) + (−83.73)

A random sample of 20 purchases showed the amounts in the table (in $). The mean is $49.57 and the standard deviation is $20.28.

son4ous [18]

Answer:

The 98% confidence interval for the mean purchases of all customers is ($37.40, $61.74).

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.98}{2} = 0.01$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.01 = 0.99$ , so $z = 2.325$

Now, find M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

$M = 2.325*\frac{20.28}{\sqrt{20}} = 12.17$

The lower end of the interval is the mean subtracted by M. So it is 49.57 - 12.17 = $37.40.

The upper end of the interval is the mean added to M. So it is 49.57 + 12.17 = $61.74.

The 98% confidence interval for the mean purchases of all customers is ($37.40, $61.74).

3 0

3 years ago

The line AB has the midpoint of (2,5) A has coordinates (1,7) find the coordinates of B

Pavel [41]

Answer:

Point B is at (3,3)

Step-by-step explanation:

the mid point is (2,5) and A is at (1,7)

first find the slope:

y1 - y2/x1 - x2

7 - 5/1 - 2

2/-1

-2/1

then go down 2 units and right 1 unit from (2,5):

(2 + 1, 5 - 2) => (3,3)

6 0

3 years ago

Plzzzzzzzzzzzzzzzzzz help quick

Bezzdna [24]

Answer:

The correct way to set up the slope formula for the line that passes through points (5 , 0) and (6 , -6) is $\frac{-6-0}{6-5}$ ⇒ C

Step-by-step explanation:

The formula of the slope of a line passes through points $(x_{1},y_{1})$ and $(x_{2},y_{2})$

is $m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}$

∵ The line passes through points (5 , 0) and (6 , -6)

∴ $x_{1}$ = 5 and $x_{2}$ = 6

∴ $y_{1}$ = 0 and $y_{2}$ = -6

Substitute these values in the formula of the slope

∵ $m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}$

∴ $m=\frac{-6-0}{6-5}$

Let us look to the answer and find the same formula

The answer is:

The correct way to set up the slope formula for the line that passes through points (5 , 0) and (6 , -6) is $\frac{-6-0}{6-5}$

8 0

3 years ago

According to the article "Characterizing the Severity and Risk of Drought in the Poudre River, Colorado" (J. of Water Res. Plann

mihalych1998 [28]

Answer:

(a) P (Y = 3) = 0.0844, P (Y ≤ 3) = 0.8780

(b) The probability that the length of a drought exceeds its mean value by at least one standard deviation is 0.2064.

Step-by-step explanation:

The random variable Y is defined as the number of consecutive time intervals in which the water supply remains below a critical value y₀.

The random variable Y follows a Geometric distribution with parameter p = 0.409.

The probability mass function of a Geometric distribution is:

$P(Y=y)=(1-p)^{y}p;\ y=0,12...$

(a)

Compute the probability that a drought lasts exactly 3 intervals as follows:

$P(Y=3)=(1-0.409)^{3}\times 0.409=0.0844279\approx0.0844$

Thus, the probability that a drought lasts exactly 3 intervals is 0.0844.

Compute the probability that a drought lasts at most 3 intervals as follows:

P (Y ≤ 3) = P (Y = 0) + P (Y = 1) + P (Y = 2) + P (Y = 3)

$=(1-0.409)^{0}\times 0.409+(1-0.409)^{1}\times 0.409+(1-0.409)^{2}\times 0.409\\+(1-0.409)^{3}\times 0.409\\=0.409+0.2417+0.1429+0.0844\\=0.8780$

Thus, the probability that a drought lasts at most 3 intervals is 0.8780.

(b)

Compute the mean of the random variable Y as follows:

$\mu=\frac{1-p}{p}=\frac{1-0.409}{0.409}=1.445$

Compute the standard deviation of the random variable Y as follows:

$\sigma=\sqrt{\frac{1-p}{p^{2}}}=\sqrt{\frac{1-0.409}{(0.409)^{2}}}=1.88$

The probability that the length of a drought exceeds its mean value by at least one standard deviation is:

P (Y ≥ μ + σ) = P (Y ≥ 1.445 + 1.88)

= P (Y ≥ 3.325)

= P (Y ≥ 3)

= 1 - P (Y < 3)

= 1 - P (X = 0) - P (X = 1) - P (X = 2)

$=1-[(1-0.409)^{0}\times 0.409+(1-0.409)^{1}\times 0.409\\+(1-0.409)^{2}\times 0.409]\\=1-[0.409+0.2417+0.1429]\\=0.2064$

Thus, the probability that the length of a drought exceeds its mean value by at least one standard deviation is 0.2064.

6 0

3 years ago

How far is the woman traveling if she is driving 25mph?

Degger [83]

Answer:

C.12.50

Step-by-step explanation:

25 mph is your rate. Whilst your time is half of an hour. 25 * .5 = 12.5.

5 0

3 years ago