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3 years ago

Can somebody please help with these two questions?

Mathematics

1 answer:

Nitella [24]3 years ago

6 0

Answer:

#3: x is approximately 0.37, -5.37, #4: x is approximately 4.19, -1.19

Step-by-step explanation:

You can solve using the quadratic equation or by solving with the perfect square

$\frac{-b+/-\sqrt{b^{2}-4ac} }{2a}$ = $x^{2}+5x-2=0\\ \frac{-5+/-\sqrt{5^{2}-4(1)(-2) }}{2(1)}$

x is approximately 0.37, -5.37

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Step-by-step explanation:

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The equation x^2−8x−5=0 can be transformed into the equation (x−p)^2=q, where p and q are real numbers. What is the value of q?

Setler79 [48]

Answer:

x = 5

x = 3

Step-by-step explanation:

The first term is, x2 its coefficient is 1 .

The middle term is, -8x its coefficient is -8 .

The last term, "the constant", is +15

Step-1 : Multiply the coefficient of the first term by the constant 1 • 15 = 15

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2 years ago

Suppose a lawn and garden company wants to determine the current percentage of customers who use fertilizer on their lawns. How

marishachu [46]

Answer:

n=601

Step-by-step explanation:

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.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

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 value 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 value would be given by:

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

The confidence interval for the mean is given by the following formula:

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

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 $ME =\pm 0.04$ 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)

Since we don't have a prior estimation for the proportion we can use 0.5 as estimation. And replacing into equation (b) the values from part a we got:

$n=\frac{0.5(1-0.5)}{(\frac{0.04}{1.96})^2}=600.25$

And rounded up we have that n=601

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3 years ago