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3 years ago

Given f(x)= 7x-5. Find the value of f(8)

Mathematics

1 answer:

e-lub [12.9K]3 years ago

8 0

Answer: 52

Explanation:

You need to replace the x-values with 8 to solve this. So, the equation would look like this. f(8)= 7 x 8 - 5

7 times 8 is 56. 56 minus four is 52 which is your answer.

If you needed to graph this then it would look like this... (8, 52)

The 8 is in the input because it is the x-value (we replace x with 8) and 52 is output/range/y-value because it is the answer.

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A simple random sample of 20 days in which Parsnip ate seeds was selected, and the mean amount of time it took him to eat the se

bearhunter [10]

Answer:

$(14.5-13.9) -1.69 \sqrt{\frac{3.98^2}{20}+ \frac{4.03^2}{17}} = -1.63$

$(14.5-13.9) +1.69 \sqrt{\frac{3.98^2}{20}+ \frac{4.03^2}{17}} = 2.83$

And the confidence interval for this case $-1.63 \leq \mu_1 -\mu_2 \leq 2.83$

Step-by-step explanation:

We know the following info from the problem

$\bar X_1 = 14.5$ sample mean for the group 1

$s_1 = 3.98$ the standard deviation for the group 1

$n_1= 20$ the sample size for group 1

$\bar X_2 = 13.9$ sample mean for the group 2

$s_1 = 4.03$ the standard deviation for the group 2

$n_2= 17$ the sample size for group 2

We have all the conditions satisifed since we have random samples.

We want to construct a confidence interval for the true difference of means and the correct formula for this case is:

$(\bar X_1 -\bar X_2) \pm t_{\alpha/2}\sqrt{\frac{s^2_1}{n_1} +\frac{s^2_2}{n_2}}$

The degrees of freedom are given :

$df = n_1 +n_2- 2 = 20+17-2=35$

The confidence level is 0.9 or 90% and the significance level is $\alpha=1-0.9=0.1$ and $\alpha/2 = 0.05$ and the critical value for this case is:

$t_{\alpha/2} = 1.69$

And replacing the info given we got:

$(14.5-13.9) -1.69 \sqrt{\frac{3.98^2}{20}+ \frac{4.03^2}{17}} = -1.63$

$(14.5-13.9) +1.69 \sqrt{\frac{3.98^2}{20}+ \frac{4.03^2}{17}} = 2.83$

And the confidence interval for this case $-1.63 \leq \mu_1 -\mu_2 \leq 2.83$

5 0

3 years ago

The causes of land pollutions are

Sergeu [11.5K]

Answer:

Step-by-step explanation:

Pollution can be defined as the introduction of harmful substances (man-made or natural) into the environment.

There are four major types of pollution:

1. Land pollution

2. Water pollution

3. Air pollution

4. Noise pollution

Land pollution refers to the gradual disintegration of the earth surface.

Causes of land pollution

1. Deforestation: The continuous cutting down of trees in the forest.

2. Erosion: The gradual disintegration of soil caused by the action of water.

3. Harmful agricultural practices such as bush burning, introducing toxic substances such as pesticides into the soil

4. Increased industrial waste due to increase in the number of industries

5. Mining of natural resources from the earth surface

6. Construction of bridges, railways and roads

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3 years ago

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