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3 years ago

15 = x + 4 whats the answer

Mathematics

1 answer:

stealth61 [152]3 years ago

4 0

Answer:

Step-by-step explanation:

15-4 = x

15-4 = 11

x = 11

to isolate x, you move 4 to the other side and it becomes 15-4 = x

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A homemade loaf of bread turns out to be a perfect cube. Five slices of bread, each 0.6 inch thick, are cut from one end of the

erastovalidia [21]

A cube has all sides of equal length.

So let the side be x

that will be length = width = height = x

Now, when we cut the loaf into 5 equal slices, the length and height of the slices are the same as the original loaf. But the width will become less with each slicing. Here the width corresponds to the thickness of the slices.

For each slice the dimensions are -

Length = x

height = x

width = 0.6

Volume of the original loaf is x³.

Volume of 5 slices is 5(x * x * 0.6).

Volume that is left after the cutting the slices is 235 inch³.

So, equation of the volume is=

x³ - 5(0.6x²) = 235

Solve for x using this equation.

x³ - 3x² = 235

x³ - 3x² - 235 = 0

Using a graph calculator to find the roots, we get

x = 7.35

Hence the dimensions of the original loaf is 7.35 inches for each side.

Please find attached the graph.

7 0

3 years ago

A doctor wants to estimate the mean HDL cholesterol of all 20- to 29-year-old females. The number of subjects needed to estima

Ludmilka [50]

Answer:

$n=(\frac{1.64(14.7)}{3})^2 =64.57 \approx 65$

So the answer for this case would be n=65 rounded up to the nearest integer

And the sample size would decrease by 160-65=95 subjects

Step-by-step explanation:

1) Previous concepts

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".

$\bar X$ represent the sample mean for the sample

$\mu$ population mean (variable of interest)

s represent the sample standard deviation

n represent the sample size

ME represent the margin of error

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

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

2) Solution to the problem

Since the new Confidence is 0.90 or 90%, the value of $\alpha=0.1$ and $\alpha/2 =0.05$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.05,0,1)".And we see that $z_{\alpha/2}=1.64$