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3 years ago

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Plz help, will mark brainliest

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lisov135 [29]3 years ago

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In a study to establish the absolute threshold of hearing, 80 male college freshmen were each seated in a soundproof room and a

Norma-Jean [14]

Answer:

Step-by-step explanation:

Hello!

To study the threshold of hering the researcher took a random sample of 80 male college freshmen.

The students underwent an audiometry test where a tome was played and they had to press a button when they detected it. The researcher recorded the lowest stimulus level at which the tone was detected obtaining a sample mean of X[bar]= 22.2 dB and a standard deviation of S= 2.1 dB

To estimate the population mean, since we don't have information about the variable distribution but the sample size is greater than 30, you can use the approximation of the standard normal distribution:

X[bar] ± $Z_{1-\alpha /2} * \frac{S}{\sqrt{n} }$

Where the semiamplitude or margin of error of the interval is:

d= $Z_{1-\alpha /2} * \frac{S}{\sqrt{n} }$

Using a 95% level $Z_{0.975}= 1.965$

d= 1.965 * $\frac{2.1}{\sqrt{80} }$

d= 0.46

The point estimate of the population mean of the threshold of hearing for male college freshmen is X[bar]= 22.2 db

And the estimation using a 95%CI is [21.74;22.66]

I hope this helps!

8 0

3 years ago

For each sentence below, find the value of x that makes each sentence true.

vitfil [10]

<u>ANSWER</u>

1. $x=\frac{1}{2}$

2. $x=1$

<u>QUESTION 1</u>

The first sentence is $(5^{\frac{1}{5}})^5=25^x$ .

Recall that;

$(a^m)^n=a^{mn}$

We simplify the left hand side by applying this property to get;

$5^{\frac{1}{5}\times 5}=25^x$ .

$\Rightarrow 5^{1}=25^x$ .

We now rewrite the right hand side too in an index form to obtain;

$\Rightarrow 5^{1}=5^{2x}$

We now equate the exponents to get;

$\Rightarrow 1=2x$ .

$\Rightarrow \frac{1}{2}=x$

$\Rightarrow x=\frac{1}{2}$ .

<u>QUESTION 2</u>

The second sentence is $(8^{\frac{1}{3}})^2=4^x$

We simplify the left hand side first to get;

$(2^{3\times \frac{1}{3}})^2=4^x$

$2^2=4^x$

We now rewrite the left hand side too in index form to obtain;

$2^2=2^{2x}$

We equate the exponents to get;

$2=2x$

This implies that;

$1=x$

or

$x=1$

4 0

2 years ago

What are the domain and range of f(x) = |x + 6|?

san4es73 [151]

9514 1404 393

Answer:

domain: all real numbers
range: y ≥ 0

Step-by-step explanation:

The function is defined for all values of x, so its domain is all real numbers.

The function can produce values of f(x) that are 0 or greater, so its range is ...

y ≥ 0

4 0

2 years ago

11. What is the length of the missing side, x?

Dimas [21]

Answer:

x = 40 in

Step-by-step explanation:

the missing angle in the triangle on the left is

180° - (74 + 51)° = 180° - 125° = 55°

the missing angle in the triangle on the right is

180° - (74 + 55)° = 180° - 129° = 51°

the 2 triangles have 3 pairs of congruent angles and are therefore congruent.

Corresponding sides and angles are then congruent

consider the corresponding sides opposite 74° , that is x and 40 in , so

x = 40 in

8 0

7 months ago

Help me plz help assao

8_murik_8 [283]

next month she will earn 4943.25 !

4 0

2 years ago