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2 years ago

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Smart phone users between 18 and 24 years of age send on average 64 text messages per day with a standard deviation of 10 messag

es about what percentage of smartphone users in this age groups in less than 51 text messages per day

1 answer:

inna [77]2 years ago

4 0

Answer:

9.68%

Step-by-step explanation:

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Answer:456 thatas the answer

Step-by-step explanation:

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2 years ago

It is advertised that the average braking distance for a small car traveling at 65 miles per hour equals 120 feet. A transportat

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Answer:

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the mean is equal to 120 or not, the system of hypothesis would be:

Null hypothesis: $\mu = 120$

Alternative hypothesis: $\mu \neq 120$

Part 2

Calculate the statistic

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

$z=\frac{114-120}{\frac{22}{\sqrt{36}}}=-1.636$

P-value

Since is a two sided test the p value would be:

$p_v =2*P(z$

Step-by-step explanation:

Data given and notation

$\bar X=114$ represent the sample mean

$\sigma=22$ represent the population standard deviation

$n=36$ sample size

$\mu_o =120$ represent the value that we want to test

$\alpha$ represent the significance level for the hypothesis test.

t would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

Part 1

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the mean is equal to 120 or not, the system of hypothesis would be:

Null hypothesis: $\mu = 120$

Alternative hypothesis: $\mu \neq 120$

If we analyze the size for the sample is > 30 and we know the population deviation so is better apply a z 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".

Part 2

Calculate the statistic

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

$z=\frac{114-120}{\frac{22}{\sqrt{36}}}=-1.636$

P-value

Since is a two sided test the p value would be:

$p_v =2*P(z$

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3 years ago

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Convert the problem to an equation using the percentage formula: P% * X = Y.
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2 years ago

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Dahasolnce [82]

Answer:

<u>9π m²</u>

Step-by-step explanation:

We will need calculate the area of the top, the base and sides.

Area of the top=πr²

Area of the base=πr²

Area of the side: 2πrh

Surface area of a cylinder: area of the top + area of the base +area of the side

Surface area of a cylinder=πr²+πr²+2πrh=2πr²+2πrh=2πr(r+h)

Data:

r=1.5 m

h=1.5 m

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