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3 years ago

PLEASE HELP!!!!!!!!!!!!

Mathematics

2 answers:

tresset_1 [31]3 years ago

8 0

Answer= 21x+14
7(3x)+ 7(2)= 21x+14

Igoryamba3 years ago

3 0

<h3>Answer: 21x+14 (choice A)</h3>

Explanation:

Use the distribution rule to multiply the outer 7 by each term inside

7 times 3x = 21x
7 times 2 = 14

We go from 7(3x+2) to 21x+14

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Assume the sample variances to be continuous measurements. Find the probability that a random sample of 25observations, from a n

konstantin123 [22]

Answer:

a) $P(4S^2 > 4*9.1) = P(\chi^2_{24} >36.4) = 0.0502$

b) $P(13.848$ Step-by-step explanation:

Previous concepts

The Chi Square distribution is the distribution of the sum of squared standard normal deviates .

For this case we assume that the sample variance is given by $S^2$ and we select a random sample of size n from a normal population with a population variance $\sigma^2$ . And we define the following statistic:

$T = \frac{(n-1) S^2}{\sigma^2}$

And the distribution for this statistic is $T \sim \chi^2_{n-1}$

For this case we know that n =25 and $\sigma^2 = 6$ so then our statistic would be given by:

$\chi^2 = \frac{(n-1)S^2}{\sigma^2}=\frac{24 S^2}{6}= 4S^2$

With 25-1 =24 degrees of freedom.

Solution to the problem

Part a

For this case we want this probability:

$P(S^2 > 9.1)$

And we can multiply the inequality by 4 on both sides and we got:

$P(4S^2 > 4*9.1) = P(\chi^2_{24} >36.4) = 0.0502$

And we can use the following excel code to find it: "=1-CHISQ.DIST(36.4,24,TRUE)"

Part b

For this case we want this probability:

$P(3.462 < S^2$

If we multiply the inequality by 4 on all the terms we got:

$P(3.462*4 < 4S^2 < 4*10.745)= P(13.848< \chi^2$ And we can find this probability like this: $P(13.848$ And we use the following code to find the answer in excel: "=CHISQ.DIST(42.98,24,TRUE)-CHISQ.DIST(13.848,24,TRUE)"

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Step-by-step explanation:

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Stolb23 [73]

Answer:

2 2/7

Step-by-step explanation:

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3 years ago

Last year Peter spent a total of 8 1/6 hours on community service. Visits to old folks' homes made up 4/7 of the total time. How

zhannawk [14.2K]

Answer:

A. 4 2/3 hours

B. (i) 9 4/5 hours

(ii) 1 19/30

Step-by-step explanation:

Firstly, to find the number of hours he used in visiting old folks, what we have to do is to multiply the fraction of hours he used by the total number of hours.

Mathematically, that would be;

4/7 * 8 1/6

8 1/6 is same as 49/6

So the number of hours he spent visiting old folks would be ;

49/6 * 4/7 = 14/3 = 4 2/3 hours

B. What we do here is simply multiply the fraction now by what he spent last year.

That would be 1 1/5 * 8 1/6 hours

= 6/5 * 49/6 = 49/5 = 9 4/5 hours

ii) Now we want to know how much more time will be spent this year than last year.

What to do here simply is to subtract the time taken last year from what we have this year

That would be;

49/5 - 49/6 = 49/30 = 1 19/30