Which is greatest? .444 .544 .554 .321

B. (4,-7)

zvonat [6]

Answer:

b)-3

c)17

d)-11

Step-by-step explanation:

4,-7)

-3

5 0

3 years ago

23. A certain type of gasoline is supposed to have a mean octane rating of at least 90. Suppose measurements are taken on of 5 r

Nostrana [21]

Answer:

a) $p_v =P(Z$

b) Since $p_v$ we can reject the null hypothesis at the significance level given. So based on this we can commit type of Error I.

Because Type I error " is the rejection of a true null hypothesis".

c) $P(\bar X >90)=1-P(Z$

$1-P(Z$

d) For this case we need a z score that accumulates 0.02 of the area on the right tail and 0.98 on the left tail and this value is z=2.054

And we can use this formula:

$2.054=\frac{90-89}{\frac{0.8}{\sqrt{n}}}$

And if we solve for n we got:

$n = (\frac{2.054 *0.8}{1})^2=2.7 \approx 3$

Step-by-step explanation:

Previous concepts and data given

The margin of error is the range of values below and above the sample statistic in a confidence interval.

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".

We can calculate the sample mean and deviation with the following formulas:

$\bar X = \frac{\sum_{i=1}^n X_i}{n}$

$s=\sqrt{\sum_{i=1}^n (X_i -\bar X)^2}{n-1}$

$\bar X=88.96$ represent the sample mean

$s=1.011$ represent the sample standard deviation

n=5 represent the sample selected

$\alpha$ significance level

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the mean is less than 90, the system of hypothesis would be:

Null hypothesis: $\mu \geq 90$

Alternative hypothesis: $\mu < 90$

If we analyze the size for the sample is < 30 and we don't know the population deviation so is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:

$z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}$ (1)

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

Calculate the statistic

We can replace in formula (1) the info given like this:

$z=\frac{88.96-90}{\frac{0.8}{\sqrt{5}}}=-2.907$

Part a

P-value

First we need to calculate the degrees of freedom given by:

$df=n-1=5-1 = 4$

Then since is a left tailed test the p value would be:

$p_v =P(Z$

Part b

Since $p_v$ we can reject the null hypothesis at the significance level given. So based on this we can commit type of Error I.

Because Type I error " is the rejection of a true null hypothesis".

Part c

We want this probability:

$P(\bar X$

The best way to solve this problem is using the normal standard distribution and the z score given by:

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

If we apply this formula to our probability we got this:

$P(\bar X >90)=1-P(Z$

$1-P(Z$

Part d

For this case we need a z score that accumulates 0.02 of the area on the right tail and 0.98 on the left tail and this value is z=2.054

And we can use this formula:

$2.054=\frac{90-89}{\frac{0.8}{\sqrt{n}}}$

And if we solve for n we got:

$n = (\frac{2.054 *0.8}{1})^2=2.7 \approx 3$

7 0

3 years ago

41. Suppose a family drives at an average rate of 60 mi/h on the way to visit relatives and then at an average rate of 40 mi/h o

Afina-wow [57]

Answer:

The answer is below

Step-by-step explanation:

a) Let x represent the time taken to drive to see the relatives and let d be the distance travelled to go, hence:

60 mi/h = d/x

d = 60x

When returning, they still travelled a distance d, since the return trip takes 1 h longer than the trip there, therefore:

40 mi/h = d/(x+1)

d = 40(x + 1) = 40x + 40

Equating both equations:

60x = 40x + 40

60x - 40x = 40

20x = 40

x = 40/20

x = 2 h

The time taken to drive there = x = 2 hours

b) The time taken for return trip = x + 1 = 2 + 1 = 3 hours

c) The distance d = 60x = 60(2) = 120 miles

The total distance to and fro = 2d = 2(120) = 240 miles

The total time to and fro = 2 h + 3 h = 5 h

Average speed = total distance / total time = 240 miles / 5 h = 48 mi/h

5 0

3 years ago

How do you plot 2/3 on a number line

NemiM [27]

Answer:

_|_____________________|_____________________|_

1/3 2/3 3/3

Step-by-step explanation:

draw a line:

____________________________________________

then divide the line by three's:

_|_____________________|_____________________|_

then mark the first part 1/3

the second 2/3 and third 3/3:

_|_____________________|_____________________|_

1/3 2/3 3/3

5 0

3 years ago

Stephen charges $25 for each lawn he mows. Identify the dependent and independent variable

alex41 [277]

Because Stephen always gets $25 it doesn't change making it the Dependent Variable, but how many lawns she mows can change making it Independent.

Dependent = $25

Independent = Lawns Mowed

3 0

3 years ago