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2 years ago

what answer is this please help i'm in a test right now i'll give you more points if you give me the right answer no guessing k

Mathematics

2 answers:

larisa86 [58]2 years ago

5 0

Answer:

c ...........................

bulgar [2K]2 years ago

3 0

The answer would be C because it says 2.25 every hour so times by 3 you get 6.75

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It took Debbie 3.6 hours to drive to her mother's house on Thursday morning. On her return trip on Friday night, traffic was hea

Mrac [35]

Answer:

36 mph

Step-by-step explanation:

d = rt

d = (x)(3.6)

d = (x-4)(4)

3.6x = 4x - 16

-0.4x = -16

x = 40

Her speed was 40 on Thursday, so 36 on Friday

7 0

2 years ago

Kiero saber la tabla numérica de 14

Arte-miy333 [17]

I think it is 8 right i not sure

8 0

3 years ago

Juan has a piano recital next month.last week he practiced for 8 hours in the morning and 7 hours in the afternoon. Each practic

valentina_108 [34]

Well if it was 8 hours in the morning and 7 in the evening per day of the week it would be 105 divided by 2 for the number of sessions would equal to 52.5 sessions. if it was just that amount of time from that whole week, it would be 15 hours divided by 2 which would give you 7.5... Did that help?

3 0

3 years ago

Read 2 more answers

Your state is considering raising the legal age for consumption of alcoholic beverages to 21 years old. How large a sample size

julsineya [31]

Answer:

$n=\frac{0.5(1-0.5)}{(\frac{0.01}{2.58})^2}=16641$

And rounded up we have that n=16641

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

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

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:

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

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 $ME =\pm 0.01$ 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)

For this case we can use as estimator for the proportion $\hat p =0.5$ , since we don't have any other previous info. And replacing into equation (b) the values from part a we got:

$n=\frac{0.5(1-0.5)}{(\frac{0.01}{2.58})^2}=16641$

And rounded up we have that n=16641

8 0

3 years ago

Solve 4 cos2x-3 = 0 for all real values of x.

vichka [17]

4 cos² x - 3 = 0

4 cos² x = 3

cos² x = 3/4

cos x = ±(√3)/2

Fixing the squared cosine doesn't discriminate among quadrants. There's one in every quadrant

cos x = ± cos(π/6)

Let's do plus first. In general, cos x = cos a has solutions x = ±a + 2πk integer k

cos x = cos(π/6)

x = ±π/6 + 2πk

Minus next.

cos x = -cos(π/6)

cos x = cos(π - π/6)

cos x = cos(5π/6)

x = ±5π/6 + 2πk

We'll write all our solutions as

x = { -5π/6, -π/6, π/6, 5π/6 } + 2πk integer k

3 0

3 years ago