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4 years ago

How do you simplify -3 1/2- -12 1/4

Mathematics

1 answer:

astraxan [27]4 years ago

8 0

To make the problem simpler, turn it to an improper fraction.

-7/2--49/48

-7/2+49/48

They have to have same dnominator to add.

-168/48+49/48

-119/48

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It is known that the population variance equals 484. With a .95 probability, the sample size that needs to be taken if the desir

Ksju [112]

Answer:

We need a sample size of at least 75.

Step-by-step explanation:

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 $1-\alpha$ .

So it is z with a pvalue of $1-0.025 = 0.975$ , so $z = 1.96$

Now, we 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.

The standard deviation is the square root of the variance. So:

$\sigma = \sqrt{484} = 22$

With a .95 probability, the sample size that needs to be taken if the desired margin of error is 5 or less is

We need a sample size of at least n, in which n is found when M = 5. So

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

$5 = 1.96*\frac{22}{\sqrt{n}}$

$5\sqrt{n} = 43.12$

$\sqrt{n} = \frac{43.12}{5}$

$\sqrt{n} = 8.624$

$(\sqrt{n})^{2} = (8.624)^{2}$

$n = 74.4$

We need a sample size of at least 75.

6 0

4 years ago

Read 2 more answers

Which equation could be used to find the height of the flagpole?

Andrew [12]

Given a fragpole which makes a right angle with the point of observation with the angle of elevation as 50°.

Let x be the height of the flagpole, then

$\sin50^o= \frac{x}{5}$

Therefore, the equation that could be used to find the height of the flagpole is
x/5 = sin 50

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3 years ago

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olga nikolaevna [1]

Answer:

a kite or a square

Step-by-step explanation:

The fact that the diagonals are congruent is irrelevant, unless you also know something about where they cross each other.

A kite has perpendicular diagonals. If they happen to bisect each other, then the result is a rhombus. If the diagonals are congruent, then that rhombus is a square.

Other ways to get there

A pair of congruent diagonals that cross each other symmetrically will define a trapezoid. If they also bisect each other, the result is a rectangle. If the diagonals of that rectangle are perpendicular, then it is a square.

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3 years ago

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jeka57 [31]

A system of linear equations will have no solution when the two lines making up the equation are parallel. Here, a system having x + y = 2 will have no solution if the second equation is x + y = a. where a is any real number.

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4 years ago

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Nookie1986 [14]

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Step-by-step explanation:

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