1) what is the answer to 5(3x-2y)+2(x+2y)-3(3x-2y)?

1 answer:

4 0

So first we want to distribute. (#1)

So, using the distributive property, we can:

5 * 3x - 2y * 5 + 2x + 2 * 2y - 3 * 3x - 3 * 2y

or

15x - 10y + 2x + 4y - 9x - 6y

Now just combine like terms

8x -12y

So for #1 it should be a.

#2: 2x - 3 + 3x - 5

Combine Like Terms:

2x + 3x - 3 - 5

5x - 8

So it should be b.

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A phone manufacturer wants to compete in the touch screen phone market. He understands that the lead product has a battery life

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The null hypothesis is $H_0: \mu \leq 10$

The alternative hypothesis is $H_1: \mu > 10$

b-1) The value of the test statistic is t = 1.86.

b-2) The p-value is of 0.0348.

Step-by-step explanation:

Question a:

Test if the battery life is more than twice of 5 hours:

Twice of 5 hours = 5*2 = 10 hours.

At the null hypothesis, we test if the battery life is of 10 hours or less, than is:

$H_0: \mu \leq 10$

At the alternative hypothesis, we test if the battery life is of more than 10 hours, that is:

$H_1: \mu > 10$

b-1. Calculate the value of the test statistic.

The test statistic is:

We have the standard deviation for the sample, so the t-distribution is used to solve this question

$t = \frac{X - \mu}{\frac{s}{\sqrt{n}}}$

In which X is the sample mean, $\mu$ is the value tested at the null hypothesis, s is the standard deviation and n is the size of the sample.

10 is tested at the null hypothesis:

This means that $\mu = 10$

In order to test the claim, a researcher samples 45 units of the new phone and finds that the sample battery life averages 10.5 hours with a sample standard deviation of 1.8 hours.

This means that $n = 45, X = 10.5, s = 1.8$