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3 years ago

13

Joshua is putting in a new circular shaped fire pit in his backyard. The diameter of the fire pit is 4 feet. What area of the ba

ckyard does the fire pit cover?

1 answer:

Citrus2011 [14]3 years ago

4 0

Answer:

A≈12.57ft²

This is the answer ^

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Ahmed was invited at a party at his friend’s place at 20:00 hours. He left the house at 17:00 hours and travelled in his car at

WARRIOR [948]

Answer:

yes he did make it, when he left at 17:00 he had 3:00 hours to make it to the party. if you divide 200/80=2.5 meaning he's able to make it in 2.5 hours.

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3 years ago

What is 0.08 written as a percent

andrew11 [14]

0.08 can be written as 8%

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3 years ago

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5 - (-9 ) subtracting intergers

ruslelena [56]

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Step-by-step explanation:

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3 years ago

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A medical researcher needs 37 people to test the effectiveness of an experimental drug. If 101 people have volunteered for the t

Rashid [163]

Answer:

The number of ways to select 37 people from 101 is, 5,397,234,129,638,871,133,346,507,775.

Step-by-step explanation:

In mathematics, the procedure to select k items from n distinct items, without replacement, is known as combinations.

The formula to compute the combinations of k items from n is given by the formula:

${n\choose k}=\frac{n!}{k!\cdot (n-k)!}$

Compute the number of ways to select 37 people from 101 as follows:

${101\choose 37}=\frac{101!}{37!\cdot (101-37)!}$

$=\frac{101!}{37!\times 64!}\\\\=\frac{101\times 100\times 99\times....64!}{37!\times 64!}\\\\=5397234129638871133346507775$

Thus, the number of ways to select 37 people from 101 is, 5,397,234,129,638,871,133,346,507,775.

5 0

3 years ago

Engineers at a large automobile manufacturing company are trying to decide whether to purchase brand A or brand B tires for the

andre [41]

Answer:

$s_p =\sqrt{\frac{(12 -1)(5100)^2 +(12-1)(5900)^2}{12 +12 -2}}=5514.526$

$t=\frac{(37900-39800)-0}{5514.526\sqrt{\frac{1}{12}+\frac{1}{12}}}}=-0.844$

$p_v =2*P(t_{22}$

Comparing the p value with a significance level for example $\alpha=0.1$ we see that $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can conclude that the true means are not significantly different.

Step-by-step explanation:

Data given and notation

$\bar X_{A}=37900$ represent the mean for A

$\bar X_{B}=39800$ represent the mean for B

$s_{A}=5110$ represent the sample standard deviation for A

$s_{B}=5900$ represent the sample standard deviation for B

$n_{A}=12$ sample size for the group A

$n_{B}=12$ sample size for the group B

$\alpha$ Significance level provided

t would represent the statistic (variable of interest)

Concepts and formulas to use

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

Null hypothesis: $\mu_{A}-\mu_{B}= 0$

Alternative hypothesis: $\mu_{A} - \mu_{B}\neq 0$

We don't have the population standard deviation's but we assume that the population deviation is equal for both populations, so we can apply a t test to compare means, and the statistic is given by:

$t=\frac{(\bar X_{A}-\bar X_{B})-\Delta}{s_p\sqrt{\frac{1}{n_{A}}+\frac{1}{n_{B}}}}$ (1)

Where $s_p$ represent the standard deviation pooled given by:

$s_p =\sqrt{\frac{(n_A -1)s^2_A +(n_B -1)s^2_B}{n_A +n_B -2}}$

$s_p =\sqrt{\frac{(12 -1)(5100)^2 +(12-1)(5900)^2}{12 +12 -2}}=5514.526$

t-test: Is used to compare group means. Is one of the most common tests and is used to determine whether the means of two groups are equal to each other.

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

$t=\frac{(37900-39800)-0}{5514.526\sqrt{\frac{1}{12}+\frac{1}{12}}}}=-0.844$

P value

We need to find first the degrees of freedom given by:

$df=n_A +n_{B}-2=12+12-2=22$

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

$p_v =2*P(t_{22}$

Comparing the p value with a significance level for example $\alpha=0.1$ we see that $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can conclude that the true means are not significantly different.

6 0

4 years ago