Función inversa f(x) = 7/x -9

Mathematics

2 answers:

amm18123 years ago

8 0

Answer:

(x+9)/7

Step-by-step explanation:

Let f(x) = y;

y =7/x - 9

y + 9 = 7x

x = (y + 9)/7

Substitute x for y and X = f^{-1}(x)

f^{-1}(x) =(x+9)/7 this is the inverse of f(x)

Tanya [424]3 years ago

7 0

Answer:

F-1(x)=7/(x+9)

Step-by-step explanation:

Change F(x) to y so y=7/x -9

Swap variables x=7/y -9

Solve x+9=7/y

7/(x+9)=y

Then change y to F inverse

F-1(x)=7/(x+9)

Thats ur inverse!!!

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A fast food restaurant executive wishes to know how many fast food meals adults eat each week. They want to construct a 98% conf

adelina 88 [10]

Answer:

$n=(\frac{2.326(1.1)}{0.07})^2 =1336.006 \approx 1337$

So the answer for this case would be n=1337 rounded up to the nearest integer

Step-by-step explanation:

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)

$\sigma=1.1$ represent the population standard deviation

n represent the sample size

Solution to the problem

The margin of error is given by this formula:

$ME=z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (a)

And on this case we have that ME =0.07 and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=(\frac{z_{\alpha/2} \sigma}{ME})^2$ (b)

The critical value for 98% of confidence interval now can be founded using the normal distribution. And in excel we can use this formula to find it:"=-NORM.INV(0.01;0;1)", and we got $z_{\alpha/2}=2.326$ , replacing into formula (b) we got: