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Anastaziya [24]

3 years ago

8

A 10-ft vertical post casts a 16-in shadow at the same time a nearby cell phone tower casts a 120-ft shadow. How tall is the

cell phone tower?

1 answer:

ladessa [460]3 years ago

5 0

Either 915 ft or 917 ft

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You want to obtain a sample to estimate a population proportion. At this point in time, you have no reasonable estimate for the

Vesna [10]

Answer:

A sample size of at least 1,353,733 is required.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of .

The margin of error is:

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

98% confidence level

So $\alpha = 0.02$ , z is the value of Z that has a pvalue of $1 - \frac{0.02}{2} = 0.99$ , so $Z = 2.327$ .

You would like to be 98% confident that you esimate is within 0.1% of the true population proportion. How large of a sample size is required?

We need a sample size of at least n.

n is found when M = 0.001.

Since we don't have an estimate for the proportion, we use the worst case scenario, that is $\pi = 0.5$

So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.001 = 2.327\sqrt{\frac{0.5*0.5}{n}}$

$0.001\sqrt{n} = 2.327*0.5$

$\sqrt{n} = \frac{2.327*0.5}{0.001}$

$(\sqrt{n})^{2} = (\frac{2.327*0.5}{0.001})^{2}$

$n = 1353732.25$

Rounding up

A sample size of at least 1,353,733 is required.

5 0

3 years ago

This shape is made using three semicircles The smaller semicircle have diameters of 10cm Calculate the shaded area Take 3.142 an

AleksandrR [38]

Answer:

The shaded area is 314.2 cm²

Step-by-step explanation:

Here we note that the shape consists of two small circles and one larger circle

The diameter of the larger semicircle is subtended by the two smaller semicircles, the small semicircle closer to the left of the internal circumference of the larger semicircle is shaded one while the one on the right is without color,

Therefore,

Diameter of larger semicircle = 2 × 10 = 20 cm

Based on the diagram, the shaded area is observed to be;

Shaded area = Area of semicircle formed by larger diameter or 20 cm + Area area formed by the small semicircle close to the right of the internal circumference of the larger semicircle - Area area formed by the other smaller semicircle

Since the diameter and therefore the areas of the two small semicircles are equal, we have;

Shaded area = Area formed by the complete larger semicircle = Area of semicircle formed by larger diameter or 20 cm

∴ Shaded area = π·D²/4 = π×20²/4 = 100×3.142 cm² = 314.2 cm².

6 0

2 years ago

Whats 69.2 as a fraction ??

Vladimir79 [104]

69 and 2/10 or 20/100 pls vote me brainliest

5 0

2 years ago

Read 2 more answers

If the total labor cost is $865,000 and 12 percent is for concession staff, how much of the labor cost is for concession staff?

stepladder [879]

12% of $865,000 is $103,800

4 0

2 years ago

3x∧2±6x±x±20 sole by factorization

Trava [24]

Answer:

just look at the algebra formula and simplify to get your answer. Remember to use your powers well

8 0

1 year ago