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3 years ago

Pleaseeeeeee helppppppp

Mathematics

1 answer:

Alina [70]3 years ago

7 0

Answer:

what is the substitution method???

Step-by-step explanation:

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(2x/3)=x+2 With working out plzzz

MissTica

Answer:

x= -6

Step-by-step explanation:

2x/3=x+2

multiply each side by 3

2x/3*3=x+2*3

calculate

2x=3x+6

move variable to the left and change the sign

2x-3x=6

collect like terms

-x=6

change the signs

x= -6

5 0

3 years ago

In a survey, the planning value for the population proportion is p* = 0.35. How large a sample should be taken to provide a 95%

lions [1.4K]

Answer:

$n=\frac{0.35(1-0.35)}{(\frac{0.05}{1.96})^2}=349.59$

And rounded up we have that n=350

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".

$p$ represent the real population proportion of interest

$\aht p$ represent the estimated proportion for the sample

n is the sample size required (variable of interest)

$z$ represent the critical value for the margin of error

Solution to the problem

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})$

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by $\alpha=1-0.95=0.05$ and $\alpha/2 =0.025$ . And the critical value would be given by:

$z_{\alpha/2}=-1.96, z_{1-\alpha/2}=1.96$

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.05$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

And replacing into equation (b) the values from part a we got:

$n=\frac{0.35(1-0.35)}{(\frac{0.05}{1.96})^2}=349.59$

And rounded up we have that n=350

6 0

3 years ago

A bag contains 70 pencils out of which 15 are green and 30 blue.(i)How many pencils of other colours. are in the bag?(ii)A penci

Bas_tet [7]

Answer:

i) 25

ii) 30:70; 30 out of 70 pencils will be blue.

Step-by-step explanation:

i) 70 - (15+30)= 25 other colors in the bag.

ii) 30:70

4 0

4 years ago

I need help with <br> (6 + 4)² ÷ 4 – 8 + 6 · 8 and 16 + 3(8 + 2) + 6² ÷ 9<br> show work please!

Alex787 [66]

Better do gemdas sis

5 0

3 years ago

In a New York coupon experiment, the experiment was conducted to test the effects of the face value of coupons on the likelihood

steposvetlana [31]

Answer:

The correct approach will be "the likelihood of cashing the coupon".

Step-by-step explanation:

That what's being examined as well as calculated throughout the experiment or observational study seems to be the dependent variable (almost always widely recognized as that of the responding variable). As a consequence of the modifications to something like the independent variable, that's what modifications.
Whether large you are really at various ages would be an illustration of some kind of dependent variable.

5 0

3 years ago