PLEASE HELP 7TH GRADE MATH

What do you understand by resultant of a force

IceJOKER [234]

Answer:

When a system of forces is acting on an object, the difference between the forces is called the Resultant force. For example, a 3N force to the left and 10N force to the right gives a resultant force of 7N to the right.

Step-by-step explanation:

5 0

3 years ago

A researcher is interested in finding a 95% confidence interval for the mean number minutes students are concentrating on their

Sever21 [200]

Answer:

A. Normal

B. Between 40.08 minutes and 43.92 minutes.

C. About 95 percent of these confidence intervals will contain the true population mean number of minutes of concentration and about 5 percent will not contain the true population mean number of minutes of concentration.

Step-by-step explanation:

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

For a proportion p in a sample of size n, the sampling distribution of the sample proportion will be approximately normal with mean $\mu = p$ and standard deviation $s = \sqrt{\frac{p(1-p)}{n}}$

x% confidence interval:

A confidence interval is built from a sample, has bounds a and b, and has a confidence level of x%. It means that we are x% confident that the population mean is between a and b.

Question A:

By the Central Limit Theorem, a normal distribution.

Question B:

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 $1 - \alpha$ .

That is z with a pvalue of $1 - 0.025 = 0.975$ , so Z = 1.96.

Now, 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.

$M = 1.96\frac{12}{\sqrt{150}} = 1.92$

The lower end of the interval is the sample mean subtracted by M. So it is 42 - 1.92 = 40.08 minutes

The upper end of the interval is the sample mean added to M. So it is 42 + 1.92 = 43.92 minutes

Between 40.08 minutes and 43.92 minutes.

Question C:

x% confidence interval -> x% will contain the true population mean, (100-x)% wont.

So, 95% confidence interval:

About 95 percent of these confidence intervals will contain the true population mean number of minutes of concentration and about 5 percent will not contain the true population mean number of minutes of concentration.

3 0

3 years ago

Which function, g or h, is the inverse function for function ƒ? the function h because the graphs of ƒ and h are symmetrical abo

xz_007 [3.2K]

A function and it's inverse function, when graphed, will be symmetrical across the line y=x.
Without seeing your graphs, I can't tell you if it's g or h. Look for the function which mirrors 'f' across y=x, which is a diagonal line passing through the origin (0,0) of the graph.

4 0

3 years ago

Aubrey wants to buy a new coat that has a regular price of $185. This weekend the coat is on sale at a 33% discount what is the

sweet-ann [11.9K]

Find 33% of 185:

0.33 * 185 = 61.05

Subtract this from the regular price:

185 - 61.05 = 123.95

So the sale price is $123.95

4 0

3 years ago

Read 2 more answers

What is 4x 3y=19,6x-5y=-57?

AlekseyPX

4x+3y=19 and 6x-5y=-57
eliminate

multiply first equation by -6 and 2nd by 4
and add them

-24x-18y=-114
<u>24x-20y=-228 +</u>
0x-38y=-342

-38y=-342
divide both sides by -38
y=9
sub back

4x+3y=19
4x+3(9)=19
4x+27=19
minus 27 both sides
4x=-8
divide 4
x=-2

(x,y)
(-2,9)

3 0

3 years ago