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2 years ago

Penny reads 10

Mathematics

2 answers:

Degger [83]2 years ago

8 0

Answer:

Hr/p is 1/30 Or 1hr every 30pg

Step-by-step explanation:

kow [346]2 years ago

4 0

Answer:

Step-by-step explanation:

You might be interested in

The advertised size of a computer or television screen is actually the length of the diagonal of

andreyandreev [35.5K]

Answer:

37.5 cm

Step-by-step explanation:

See attached for reference.

let the diagonal be x,

By Pythagorean formula:

x² = (22.5)² + (30)²

x = √[(22.5)² + (30)²]

x = 37.5 cm

4 0

2 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

On monday, deborah ran 3 2/5 miles and on tuesday she ran 4 1/5 miles how many miles did she run on these 2 days togehter

Iteru [2.4K]

Convert the two fractions into simpler fractions: 3 2/5 --> 17/5 and 4 1/5 --> 21/5. Notice the the denominators are identical, so we simply add the numerators: (17 + 21)/5 = 38/5 = 7 3/5.

There is an easier way to do this, this is just the most clear way of seeing everything.

8 0

3 years ago

SOLVE THE ONES YOU CAN!

Leviafan [203]

1) 0.0123456789
2) yes
3) yes
4) 1,073,741,824
5) 1.00000000E + 15

4 0

3 years ago

a roofer charges $60 for the first hour of service call and $25 per hour for each additional hour. The roofer also charges a fee

Temka [501]

Answer:

Step-by-step explanation:

let y be the total charges

given that the hour is h

and the cost for raw material is r

therefore

1. The first hour of service call = $60

2. For each additional hour= 25h

3. 30% over the cost of the materials.= 30/100*r=0.3r

total charges

y=60+25h+0.3r

therefore the expression is

y=60+25h+0.3r

4 0

2 years ago