How do you isolate x in 1/2x+1/5y=9

Mathematics

2 answers:

Cloud [144]4 years ago

8 0

You would subtract 1/5y, and multiply both sides by 2 (1/2's reciprocal)

jasenka [17]4 years ago

5 0

Subtract 1/2x from each side
1/5y=9-1/2x
subtract 9 from each side
1/5y-9=-1/2x
multiply each side by 2
2/5y-18=-x
multiply each side by -1
-2/5y+18=x

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Jobisdone [24]

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3 0

4 years ago

The state education commission wants to estimate the fraction of tenth grade students that have reading skills at or below the e

irakobra [83]

Answer:

We need a sample size of at least 383.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

The margin of error is:

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

85% confidence level

So $\alpha = 0.15$ , z is the value of Z that has a pvalue of $1 - \frac{0.15}{2} = 0.925$ , so $Z = 1.44$ .

How large a sample would be required in order to estimate the fraction of tenth graders reading at or below the eighth grade level at the 85% confidence level with an error of at most 0.03

We need a sample size of at least n.

n is found with $M = 0.03, \pi = 0.21$