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Lisa [10]
3 years ago
13

There are 20 students in a drama class. The mean age of 12 students is 18 years. The mean age of the remaining 8 students of the

drama class is 23 years. What is the mean age of all the students in the drama class?
Mathematics
1 answer:
Marta_Voda [28]3 years ago
3 0

Answer:

Step-by-step explanation:

Total sum of age of 12 students = 12*18 = 216;

Total sum of age of 8 students = 8*23 = 184;

Total sum of age of 20 students = 216+184 = 400;

Mean age of all the students = total age / number of students;

= 400/20 = 20 year

Step-by-step explanation:

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Alexeev081 [22]

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4 0
3 years ago
Write the equation of the line that passes through (−3,1) and (2,−1) in slope-intercept form
Alex787 [66]

Answer:

y=-\frac{2}{5}x-\frac{1}{5}

Step-by-step explanation:

The equation of a line is y = mx + b

Where:

  • m is the slope
  • b is the y-intercept

First, let's find what m is, the slope of the line.

Let's call the first point you gave, (-3,1), point #1, so the x and y numbers given will be called x1 and y1.

Also, let's call the second point you gave, (2,-1), point #2, so the x and y numbers here will be called x2 and y2.

Now, just plug the numbers into the formula for m above, like this:

m = -\frac{2}{5}

So, we have the first piece to finding the equation of this line, and we can fill it into y=mx+b like this:

y=-\frac{2}{5}x + b

Now, what about b, the y-intercept?

To find b, think about what your (x,y) points mean:

  • (-3,1). When x of the line is -3, y of the line must be 1.
  • (2,-1). When x of the line is 2, y of the line must be -1.

Now, look at our line's equation so far: y=-\frac{2}{5}x + b. b is what we want, the --\frac{2}{5} is already set and x and y are just two 'free variables' sitting there. We can plug anything we want in for x and y here, but we want the equation for the line that specfically passes through the two points (-3,1) and (2,-1).

So, why not plug in for x and y from one of our (x,y) points that we know the line passes through? This will allow us to solve for b for the particular line that passes through the two points you gave!

You can use either (x,y) point you want. The answer will be the same:

  • (-3,1). y = mx + b or 1=-\frac{2}{5} * -3 + b, or solving for b: b = 1-(-\frac{2}{5})(-3).b = -\frac{1}{5}.
  • (2,-1). y = mx + b or -1=-\frac{2}{5} * 2 + b, or solving for b: b = 1-(-\frac{2}{5})(2). b = -\frac{1}{5}.

See! In both cases, we got the same value for b. And this completes our problem.

The equation of the line that passes through the points  (-3,1) and (2,-1) is y=-\frac{2}{5}x-\frac{1}{5}

8 0
3 years ago
You toss a coin and randomly select a number from 0 to 9 what is the probability of getting tails and selecting 3? 0.25 0.95 0 0
andre [41]
The correct answer is .05

To solve, find the decimal of each of the probabilities: 

Flipping Tails:  1/2 ----> .5

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Now, multiply them together: 

.5 x .10 = .05

Hope this helps!
3 0
3 years ago
Read 2 more answers
Again ... Commute times in the U.S. are heavily skewed to the right. We select a random sample of 500 people from the 2000 U.S.
VladimirAG [237]

Answer:

We conclude that the mean commute time in the U.S. is less than half an hour.

Step-by-step explanation:

We are given that a random sample of 500 people from the 2000 U.S. Census is selected who reported a non-zero commute time.

In this sample the mean commute time is 27.6 minutes with a standard deviation of 19.6 minutes.

Let \mu = <u><em>mean commute time in the U.S..</em></u>

So, Null Hypothesis, H_0 : \mu \geq 30 minutes      {means that the mean commute time in the U.S. is more than or equal to half an hour}

Alternate Hypothesis, H_A : \mu < 30 minutes     {means that the mean commute time in the U.S. is less than half an hour}

The test statistics that would be used here <u>One-sample t-test statistics</u> as we don't know about population standard deviation;

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

where, \bar X = sample mean commute time = 27.6 minutes

            s = sample standard deviation = 19.6 minutes

            n = sample of people from the 2000 U.S. Census = 500

So, <u><em>the test statistics</em></u>  =  \frac{27.6 -30}{\frac{19.6}{\sqrt{500} } }  ~ t_4_9_9

                                       =  -2.738

The value of t test statistic is -2.738.

Since, in the question we are not given with the level of significance so we assume it to be 5%. <u>Now, at 5% significance level the t table gives critical values of -1.645 at 499 degree of freedom for left-tailed test.</u>

Since our test statistic is less than the critical value of t as -2.378 < -1.645, so we have sufficient evidence to reject our null hypothesis as it will fall in the rejection region due to which <u>we reject our null hypothesis.</u>

Therefore, we conclude that the mean commute time in the U.S. is less than half an hour.

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