I need help with geometry

Mathematics

2 answers:

Soloha48 [4]3 years ago

4 0

Answer:

It 12

Step-by-step explanation:

This is because the scale factor between the triangles is 1.75, so I divide 21 by 1.75 and got 12

Hope this helped

Sergio [31]3 years ago

3 0

We first have to find 2 pairs of sides that proportional.

35/20=42/24=7/4

and 21/b should be 7/4 as well because if we want the triangles to be similar the sides should be in proportion.

21/b=7/4

84=7b

b=12

Done!

Hope this helped, any questions about this just ask in the comments and I will answer.

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The state education commission wants to estimate the fraction of tenth grade students that have reading skills at or below the e

Korolek [52]

Answer:

A sample of 499 is needed.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , 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 $1 - \frac{\alpha}{2}$ .

The margin of error is given by:

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

In this question, we have that:

$\pi = 0.21$

90% confidence level

So $\alpha = 0.1$ , z is the value of Z that has a pvalue of $1 - \frac{0.1}{2} = 0.95$ , so $Z = 1.645$ .

How large a sample would be required in order to estimate the fraction of tenth graders reading at or below the eighth grade level at the 90% confidence level with an error of at most 0.03

We need a sample of n, which is found when $M = 0.03$ . So