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3 years ago

Helpppppppp meeeeeeeeeeeeee

Mathematics

1 answer:

Semenov [28]3 years ago

5 0

Answer:

Step-by-step explanation:

(23+7²)= 23+7×7=72

72÷2²= 18

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Tania knows that the ratio of boys to girls in her class is 3:5. Since 20 of the students are girls, she says that there must be

lys-0071 [83]

Answer:

No, there are 32 students in her class.

Step-by-step explanation:

The ratio to boys and girls is

$3:5$

There are 20 girls in the classroom.

$20/5=4$

$3 \times 4= 12$

$5 \times 4 =20$

$12:20$

$12+20=32$

4 0

4 years ago

Read 2 more answers

What is the closed linear form for this sequence given a1 = 13 and an + 1 = an + 4?

Oduvanchick [21]

A1=13 and a+1 = an+4

13+1=13n+4
14=17n

3 0

3 years ago

Doug works 10.50 per hour working at a restaurant. On Friday he spend 1 3/4 hours cleaning, 2 1/3 paperwork and 1 5/12 hours ser

Lelechka [254]

1 3/4 hours of work equates to $18.375 so $18.38.

2 1/3 hours of work equates to $24.50.

1 5/12 hours of work equates to $14.875 so $14.88

Add all values $18.38+$24.50+$14.88 = $57.76

Doug has a total amount of earnings which = $57.76, good luck!

5 0

3 years ago

5.1 kilometers to meters and centermeters

DIA [1.3K]

510,000 centimeters and 5,100 meters

4 0

3 years ago

Read 2 more answers

In a college student poll, it is of interest to estimate the proportion p of students in favor of changing from a quarter-system

Contact [7]

Answer:

n=206

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".

The population proportion have the following distribution

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

Solution to the problem

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 99% of confidence, our significance level would be given by $\alpha=1-0.99=0.01$ and $\alpha/2 =0.005$ . And the critical value would be given by:

$t_{\alpha/2}=-2.58, t_{1-\alpha/2}=2.58$

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 $ME =\pm 0.09$ , we can use as prior estimate of p 0.5, since we don't have any other info provided, 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:

$n=\frac{0.5(1-0.5)}{(\frac{0.09}{2.58})^2}=205.44$

And rounded up we have that n=206

3 0

3 years ago