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3 years ago

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A professor at a local community college noted that the grades of his students were normally distributed with a mean of 74 and a

standard deviation of 10. Students who made 55 or lower on the exam failed the course. What percent of students failed the course?

1 answer:

denis-greek [22]3 years ago

6 0

Answer:

28.72% of students failed the course

Step-by-step explanation:

P(0<X<55) = normalcdf(0,55,74,10) = 0.287164928 = 28.72% of students failed the course

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The following data comparing wait times at two rides at Disney are listed below: Position Pirates Splash Mountain Sample Size 32

myrzilka [38]

Answer:

a) $(14.68 -18.77) - 2.39 \sqrt{\frac{11.87^2}{32}+\frac{16.79^2}{30}} =-12.968$

$(14.68 -18.77) + 2.39 \sqrt{\frac{11.87^2}{32}+\frac{16.79^2}{30}} =4.788$

b) $t=\frac{14.68-18.77}{\sqrt{\frac{11.87^2}{32}+\frac{16.79^2}{30}}}}=-1.10$

Step-by-step explanation:

Data given and notation

$\bar X_{A}=14.68$ represent the mean for Pirates

$\bar X_{B}=18.77$ represent the mean for Splash Mountain

$s_{A}=11.87$ represent the sample standard deviation for the sample Pirates

$s_{B}=16.79$ represent the sample standard deviation for the sample Slpash Mountain

$n_{A}=32$ sample size selected for Pirates

$n_{B}=30$ sample size selected for Splash Mountain

$\alpha=0.02$ represent the significance level for the hypothesis test.

t would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

Part a

The confidence interval would be given by:

$(\bar X_A -\bar X_B) \pm t_{\alpha/2} \sqrt{\frac{s^2_{A}}{n_{A}}+\frac{s^2_{B}}{n_{B}}}$

The degrees of freedom are given by:

$df = n_A +n_B -2 = 32+30-2 = 60$

Since we want 98% of confidence the significance level is $\alpha =1-0.98 =0.02$ and $\alpha/2 =0.01$ , we can find in the t distribution with df =60 a critical value that accumulates 0.01 of the area on each tail and we got:

$t_{\alpha/2}= 2.39$

And replacing we got for the confidence interval:

$(14.68 -18.77) - 2.39 \sqrt{\frac{11.87^2}{32}+\frac{16.79^2}{30}} =-12.968$

$(14.68 -18.77) + 2.39 \sqrt{\frac{11.87^2}{32}+\frac{16.79^2}{30}} =4.788$

Part b

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the means are equal, the system of hypothesis would be:

Null hypothesis: $\mu_{A} = \mu_{B}$

Alternative hypothesis: $\mu_{A} \neq \mu_{B}$

the statistic is given by:

$t=\frac{\bar X_{A}-\bar X_{B}}{\sqrt{\frac{s^2_{A}}{n_{A}}+\frac{s^2_{B}}{n_{B}}}}$ (1)

t-test: "Is used to compare group means. Is one of the most common tests and is used to determine whether the means of two groups are equal to each other".

Calculate the statistic

We can replace in formula (1) the info given like this:

$t=\frac{14.68-18.77}{\sqrt{\frac{11.87^2}{32}+\frac{16.79^2}{30}}}}=-1.10$

6 0

3 years ago

Another way to write 9 x 200

Katyanochek1 [597]

200+200+200+200+200+200+200+200+200

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3 years ago

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I honestly don't know how I got these answers and I have a test over it coming soon. Please explain how to find the measure of t

Tju [1.3M]

Okay so a couple of things to know to best solve this problem
1) all angles in a triangle add to 180
2) a straight line the angles above it equal 180 and the angles below it add to 180
3) vertical angles are equal (vertical angles are angles that make an X the opposite angles are called vertical angles)

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4 years ago

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The double number line shows that Toni can type 180180180 words in 222 minutes. Based on the ratio shown in the double number li

vfiekz [6]

Answer:

<h3>Toni can type words in 3 minutes is 270 words</h3>

Step-by-step explanation:

Given that the double number line shows that Toni can type 180 words in 2 minutes.

<h3>To find how many words can Toni type in 3 minutes:</h3>

From the given Toni can type 180 words in 2 minutes,

⇒ Toni can type $\frac{180}{2}$

$= 90$

<h3>∴ 90 words per minute </h3>

For Toni would be able to type words in 3 minutes is

$90\times 3$

$= 270$

<h3>∴ 270 words per minute.</h3><h3>∴ Toni can type words in 3 minutes is 270 words.</h3>

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I really need help, I haven't been to school In a while and I kinda forgot what to do. So If anyone is kind enough, please help

marissa [1.9K]

Answer:

P = 20x + 6y + 10

Step-by-step explanation:

The perimeter (P) of the figure is the sum of the sides , that is

P = 2x - y + 3x + 5y + 12 + 6x + 9x + 2y - 2 ← collect like terms

= 20x + 6y + 10

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3 years ago