8×9=(5+y)×9 , what is y?

1 answer:

5 0

8 * 9 = (5 + y) * 9
multiply 8 and 9

72 = (5 + y) * 9
use the distributive property

72 = 45 + 9y
subtract 45 from both sides

27 = 9y
divide both sides by 9 to isolate the variable

y = 3

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Jacob knows that the adult population gets, on average, eight hours of sleep each night. A hypothesis test can help him see if c

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Answer:

The t-statistic that Jacob calculates is $t = -2.71$

Step-by-step explanation:

Jacob knows that the adult population gets, on average, eight hours of sleep each night. A hypothesis test can help him see if college students are different from the adult population.

At the null hypothesis, we test if the mean is of 8 hours, that is:

$H_0: \mu = 8$

At the alternative hypothesis, we test if the mean is different of 8 hours, that is:

$H_1: \mu \neq 8$

The test statistic is:

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

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.

8 is tested at the null hypothesis:

This means that $\mu = 8$

From a sample of 101 students, Jacob tabulated that his sample of students got an average of 7.3 hours of sleep each night, with a standard deviation of 2.6.

This means that $n = 101, X = 7.3, s = 2.6$