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2 years ago

Solve the simultaneous equation 2x+4y=1 3x+5y=7b

Mathematics

1 answer:

Lyrx [107]2 years ago

8 0

Step-by-step explanation:

3x+5y=7b equation 1
2x+4y=1

2x=-4y+1

x=(-4y+1)/2
x=(-4y+1)/2 in equation 1

3×(-4y+1)/2+5y=7b

(-12y+3)/2+5y=7b

(-12y+3+10y)/2=7b

(-12y+3)/2=7b

-12y+3=14b

-12y=14b-3

y=3-14b/12
y=3-14b/12 in x=(-4y+1)/2

x=(-4×{3-14b/12}+1)/2

x=(-3+14b)/3+1/2

x=14b/3×1/2

x=7b/3

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3 years ago

A sample is BEST defined as _________.

Thepotemich [5.8K]

Answer:

(B) A selected group of participants that is representative of a larger population

Step-by-step explanation:

A sample statistic is a piece of information that you get from a fraction of the population. This information is representative of a larger population.

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(B) A selected group of participants that is representative of a larger population

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3 years ago

Brewed decaffeinated coffee contains some caffeine. We want to estimate the amount of caffeine in 8 ounce cups of decaf coffee a

rusak2 [61]

Answer:

We would have to take a sample of 62 to achieve this result.

Step-by-step explanation:

Confidence level of 95%.

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1 - 0.95}{2} = 0.025$

Now, we have to find z in the Ztable as such z has a pvalue of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.025 = 0.975$ , so Z = 1.96.

Now, find the margin of error M as such

$M = z\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

Assume that the standard deviation in the amount of caffeine in 8 ounces of decaf coffee is known to be 2 mg.

This means that $\sigma = 2$

If we wanted to estimate the true mean amount of caffeine in 8 ounce cups of decaf coffee to within /- 0.5 mg, how large a sample would we have to take to achieve this result?

We would need a sample of n.

n is found when $M = 0.5$ . So