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3 years ago

11 = 7 + 4x is what is what is what

Mathematics

1 answer:

Law Incorporation [45]3 years ago

6 0

Answer:

x = 1

Step-by-step explanation:

11 = 7 + 4x

Subtract 7 from both sides

11-7 = 7-7 + 4x

4 = 4x

Divide 4 from both sides

4/4 = 4x/4

1 = x

x = 1

Check:

11 = 7 +4(1)

11 = 7+4

11 = 11

Hope this helps. Have a nice day.

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A random sample of 100 teletype operators indicates that their salaries fluctuate quite a bit. The sample Standard deviation of

ELEN [110]

Answer:

$\frac{(99)(10)^2}{123.225} \leq \sigma^2 \leq \frac{(99)(10)^2}{77.046}$

$80.341 \leq \sigma^2 \leq 128.495$

Now we just take square root on both sides of the interval and we got:

$8.963 \leq \sigma \leq 11.336$

Step-by-step explanation:

Data given and notation

s=10 represent the sample standard deviation

$\bar x$ represent the sample mean

n=100 the sample size

Confidence=90% or 0.90

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 mean or variance 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.

The Chi Square distribution is the distribution of the sum of squared standard normal deviates .

Calculating the confidence interval

The confidence interval for the population variance is given by the following formula:

$\frac{(n-1)s^2}{\chi^2_{\alpha/2}} \leq \sigma^2 \leq \frac{(n-1)s^2}{\chi^2_{1-\alpha/2}}$

The next step would be calculate the critical values. First we need to calculate the degrees of freedom given by:

$df=n-1=100-1=99$

Since the 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 values.

The excel commands would be: "=CHISQ.INV(0.05,99)" "=CHISQ.INV(0.95,99)". so for this case the critical values are:

$\chi^2_{\alpha/2}=123.225$

$\chi^2_{1- \alpha/2}=77.046$

And replacing into the formula for the interval we got:

$\frac{(99)(10)^2}{123.225} \leq \sigma^2 \leq \frac{(99)(10)^2}{77.046}$

$80.341 \leq \sigma^2 \leq 128.495$

Now we just take square root on both sides of the interval and we got:

$8.963 \leq \sigma \leq 11.336$

5 0

3 years ago

Two friends, 7 miles apart, start walking toward each other, and they meet in an hour. If one boy walks 1 mile farther in an hou

Xelga [282]

So lets say the distance one boy travels is 'x', you can set up an equation like this:
x + x + 1 = 7
2x +1 = 7
2x = 6
x = 3
So one boy walks 3 miles in one hour, and the other walks 4 miles in one hour.
Therefore, their speeds are 3 miles per hour and 4 miles per hour respectively.

3 0

3 years ago

Read 2 more answers

Hamburger heaven is having a lunch special where customers buy one 3/4 pounds cheese burger and get one free if they set aside 1

Yuri [45]

Answer:

Step-by-step explanation:

49 hamburguers (of 3/4 pound)

Step-by-step explanation:

3/4 pound is equal to 0.75 pound

37 1/3 pounds of meat is equal to

37 + 1/3 pound = 37.3333 pounds