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2 years ago

Please help me with this #6

Mathematics

1 answer:

kirza4 [7]2 years ago

8 0

$\text{First term,}~ a = 4,\\\\\text{Common difference,}~ d = 9-4 = 5\\\\\text{Nth term} = a + (n-1) d\\\\~~~~~~~~~~~~~=4+(n-1)5\\\\~~~~~~~~~~~~~= 4+5n-5\\\\~~~~~~~~~~~~~= 5n-1\\\\\text{Hence. 80th term}~ = 5(80) -1 = 399$

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What is the mean of the data set?

andre [41]

You find the mean by adding each value then dividing the sum by the number of values there were so in this case you'd say 301 + 222 + 287 + 310 + 346 which is 1466 then divide by 5 because there are 5 values and your answer is 293.2!

I hope this helps

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3 years ago

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A grower believes that one in five of his citrus trees are infected with the citrus red mite. How large a sample should be taken

mihalych1998 [28]

Answer:

n=6147

Step-by-step explanation:

1) Notation and definitions

$X=1$ number of citrus trees that are infected with the citrus red mite.

$n=5$ random sample taken

$\hat p=\frac{1}{5}=0.2$ estimated proportion of citrus trees that are infected with the citrus red mite.

$p$ true population proportion of citrus trees that are infected with the citrus red mite.

Me=0.01 represent the margin of error desired

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

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

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The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})$

In order to find the critical values we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by $\alpha=1-0.95=0.05$ and $\alpha/2 =0.025$ . And the critical values would be given by:

$t_{\alpha/2}=-1.96, t_{1-\alpha/2}=1.96$

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.01$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

And replacing into equation (b) the values from part a we got:

$n=\frac{0.2(1-0.2)}{(\frac{0.01}{1.96})^2}=6146.56$

And rounded up we have that n=6147

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4 years ago

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romanna [79]

Answer:

$\huge\boxed{(d+7)(d-7)=d^2-49}$

Step-by-step explanation:

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3 years ago

*18 POINTS*<br> Urgent!! Please answer

Ksivusya [100]

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3 years ago

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Answer fast I want to do this

Murljashka [212]

A,b are 8,2. its an easy guess.

now that makes it easy

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4 years ago