What x2-21x-100 in standard form

A certain pen has been designed so that true average writing lifetime under controlled conditions (involving the use of a writin

Morgarella [4.7K]

Answer:

(a) We reject our null hypothesis.

(b) We fail to reject our null hypothesis.

(c) We fail to reject our null hypothesis.

Step-by-step explanation:

We are given that a certain pen has been designed so that true average writing lifetime under controlled conditions (involving the use of a writing machine) is at least 10 hr.

A random sample of 18 pens is selected.

Let $\mu$ = true average writing lifetime under controlled conditions

So, Null Hypothesis, $H_0$ : $\mu \geq$ 10 hr {means that the true average writing lifetime under controlled conditions is at least 10 hr}

Alternate Hypothesis, $H_A$ : $\mu$ < 10 hr {means that the true average writing lifetime under controlled conditions is less than 10 hr}

The test statistics that is used here is one-sample t test statistics;

T.S. = $\frac{\bar X -\mu}{\frac{s}{\sqrt{n} } }$ ~ $t_n_-_1$

where, $\bar X$ = sample mean

s = sample standard deviation

n = sample size of pens = 18

n - 1 = degree of freedom = 18 -1 = 17

Now, the decision rule based on the critical value of t is given by;

If the value of test statistics is more than the critical value of t at 17 degree of freedom for left-tailed test, then we will not reject our null hypothesis as it will not fall in the rejection region.

If the value of test statistics is less than the critical value of t at 17 degree of freedom for left-tailed test, then we will reject our null hypothesis as it will fall in the rejection region.

(a) Here, test statistics, t = -2.4 and level of significance is 0.05.

Now, at 0.05 significance level, the t table gives critical value of -1.74 at 17 degree of freedom.

Here, clearly the value of test statistics is less than the critical value of t as -2.4 < -1.74, so we reject our null hypothesis.

(b) Here, test statistics, t = -1.83 and level of significance is 0.01.

Now, at 0.051 significance level, the t table gives critical value of -2.567 at 17 degree of freedom.

Here, clearly the value of test statistics is more than the critical value of t as -2.567 < -1.83, so we fail to reject our null hypothesis.

(c) Here, test statistics, t = 0.57 and level of significance is not given so we assume it to be 0.05.

Now, at 0.05 significance level, the t table gives critical value of -1.74 at 17 degree of freedom.

Here, clearly the value of test statistics is more than the critical value of t as -1.74 < 0.57, so we fail to reject our null hypothesis.

8 0

3 years ago

Math Help? 20 Points

Pachacha [2.7K]

V= LWH so 3.75cm^3 or 3 (3/4)

Multiply those three sides and it comes out to 3.75

5 0

3 years ago

Kenzie has. 4 pages of homework to do. If she can finish 1/3 of a page in one hour how many hours will her homework take?

Maru [420]

Answer:

It will take her 4 1/3 hours

Step-by-step explanation: so you know you needed to add 4 and 1/3 and you turn the 4 into 4/1 and 1/3 and since it adding you have to have the same denominator and you multiply 1x3 and if you do it on the bottom you have to do it on top so you also do 4x3 and 4x3 is 12 and one 1x3 is 3 and so you don't have to have to do it on the other fraction because now they have the same denominator now and now you add 12/3 + 1/3 and you shall get 13/3 and then you divide 13 divided by 3 and you shall get 4 1/3 and that shall be your answer.

hope it helps you!

5 0

3 years ago

What does the transformation f(x) --> -f(x) do to the graph of f(x)

mixer [17]

Answer: D) Reflect over x-axis

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Explanation:

When we do this type of reflection, a point like (1,2) moves to (1,-2).

As another example, something like (5,-7) moves to (5,7)

The x coordinate stays the same but the y coordinate flips in sign from positive to negative, or vice versa.

We can say that $(x,y) \to (x,-y)$ as a general way to represent the transformation. Note how y = f(x), so when we make f(x) negative, then we're really making y negative.

If we apply this transformation to every point on f(x), then it will flip the f(x) curve over the horizontal x axis.

There's an example below in the graph. The point A(2,8) moves to B(2,-8) after applying that reflection rule.

8 0

3 years ago

Whats a synonym (another word) for the word median? *

borishaifa [10]

Another word for median is middle. The median is the middle number of a list of numbers.

7 0

3 years ago