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Whitepunk [10]
3 years ago
14

The scores on a test are normally distributed with a mean of 19 and a standard deviation of 5

Mathematics
1 answer:
kiruha [24]3 years ago
3 0

Answer:

24.18 is the required score to get into the top 15%.

26.03 is required to get into the 92nd percentile.

Step-by-step explanation:

On a TI-84 calculator:

You can use the invNorm function to calculate the point at a given percentage on a normal model

invNorm(area, mean, sd, tail)

Plug in the values and calculate:

invNorm(0.15, 19, 5, RIGHT)

24.18 is the required score to get into the top 15%.

92nd percentile means that this score is better than 92% of scores

Plug in values and calculate:

invNorm(0.92, 19, 5, LEFT)

26.03 is required to get into the 92nd percentile.

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Solve for x in the equation x2 - 12x+ 36 = 90
12345 [234]

Answer:

6 + 3\sqrt{10\\} or 6 - 3\sqrt{10\\}

Step-by-step explanation:

x^2 - 12x + 36 = 90

x^2 - 12x - 54 = 0

x = \frac{-b +/- \sqrt{b^{2} + 4ac }}{2a}

a = 1, b= -12, c= -54

6 + 3\sqrt{10\\} or 6 - 3\sqrt{10\\}

6 0
3 years ago
Please Help! I can’t figure this question out! Question is in the pic below..
padilas [110]
The answer is 68!!!!!!!!!
4 0
2 years ago
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.

<u><em>Let </em></u>\mu<u><em> = true average writing lifetime under controlled conditions</em></u>

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}

<u>The test statistics that is used here is one-sample t test statistics;</u>

                           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

<u>Now, the decision rule based on the critical value of t is given by;</u>

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

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

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

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.

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

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.

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

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
What is the answer to the problem (m-3)(-10)
OverLord2011 [107]

The answer is -10m + 30




8 0
3 years ago
Write an inequality for the sentence below and then solve and check it. The sum of w and nine is less than 18
Andre45 [30]

Answer:

w < 9

Step-by-step explanation:

w + 9 < 18

To solve this inequality, we MUST get the w by itself

Subtraction Property of Equality  w + 9 - 9 < 18 - 9

Answer w < 9

7 0
2 years ago
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