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3 years ago

Evaluate the mean of each data set mentally. 61, 71, 81, 91, 101

Mathematics

1 answer:

goldfiish [28.3K]3 years ago

4 0

Answer:

Step-by-step explanation:

they each go by ten

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Four buses carrying 146 high school students arrive to Montreal. The buses carry, respectively, 32, 44, 28, and 42 students. One

Naily [24]

Answer:

The expected value of X is $E(X)=\frac{2754}{73} \approx 37.73$ and the variance of X is $Var(X)=\frac{226192}{5329} \approx 42.45$

The expected value of Y is $E(Y)=\frac{73}{2} \approx 36.5$ and the variance of Y is $Var(Y)=\frac{179}{4} \approx 44.75$

Step-by-step explanation:

(a) Let X be a discrete random variable with set of possible values D and probability mass function p(x). The expected value, denoted by E(X) or $\mu_x$ , is

$E(X)=\sum_{x\in D} x\cdot p(x)$

The probability mass function $p_{X}(x)$ of X is given by

$p_{X}(28)=\frac{28}{146} \\\\p_{X}(32)=\frac{32}{146} \\\\p_{X}(42)=\frac{42}{146} \\\\p_{X}(44)=\frac{44}{146}$

Since the bus driver is equally likely to drive any of the 4 buses, the probability mass function $p_{Y}(x)$ of Y is given by

$p_{Y}(28)=p_{Y}(32)=p_{Y}(42)=p_{Y}(44)=\frac{1}{4}$

The expected value of X is

$E(X)=\sum_{x\in [28,32,42,44]} x\cdot p_{X}(x)$

$E(X)=28\cdot \frac{28}{146}+32\cdot \frac{32}{146} +42\cdot \frac{42}{146} +44 \cdot \frac{44}{146}\\\\E(X)=\frac{392}{73}+\frac{512}{73}+\frac{882}{73}+\frac{968}{73}\\\\E(X)=\frac{2754}{73} \approx 37.73$

The expected value of Y is

$E(Y)=\sum_{x\in [28,32,42,44]} x\cdot p_{Y}(x)$

$E(Y)=28\cdot \frac{1}{4}+32\cdot \frac{1}{4} +42\cdot \frac{1}{4} +44 \cdot \frac{1}{4}\\\\E(Y)=146\cdot \frac{1}{4}\\\\E(Y)=\frac{73}{2} \approx 36.5$

(b) Let X have probability mass function p(x) and expected value E(X). Then the variance of X, denoted by V(X), is

$V(X)=\sum_{x\in D} (x-\mu)^2\cdot p(x)=E(X^2)-[E(X)]^2$

The variance of X is

$E(X^2)=\sum_{x\in [28,32,42,44]} x^2\cdot p_{X}(x)$

$E(X^2)=28^2\cdot \frac{28}{146}+32^2\cdot \frac{32}{146} +42^2\cdot \frac{42}{146} +44^2 \cdot \frac{44}{146}\\\\E(X^2)=\frac{10976}{73}+\frac{16384}{73}+\frac{37044}{73}+\frac{42592}{73}\\\\E(X^2)=\frac{106996}{73}$

$Var(X)=E(X^2)-(E(X))^2\\\\Var(X)=\frac{106996}{73}-(\frac{2754}{73})^2\\\\Var(X)=\frac{106996}{73}-\frac{7584516}{5329}\\\\Var(X)=\frac{7810708}{5329}-\frac{7584516}{5329}\\\\Var(X)=\frac{226192}{5329} \approx 42.45$

The variance of Y is

$E(Y^2)=\sum_{x\in [28,32,42,44]} x^2\cdot p_{Y}(x)$

$E(Y^2)=28^2\cdot \frac{1}{4}+32^2\cdot \frac{1}{4} +42^2\cdot \frac{1}{4} +44^2 \cdot \frac{1}{4}\\\\E(Y^2)=196+256+441+484\\\\E(Y^2)=1377$

$Var(Y)=E(Y^2)-(E(Y))^2\\\\Var(Y)=1377-(\frac{73}{2})^2\\\\Var(Y)=1377-\frac{5329}{4}\\\\Var(Y)=\frac{179}{4} \approx 44.75$

8 0

3 years ago

Please answer both

iogann1982 [59]

Every function is a relation because the numbers have relationships but not every relation is a function because for it to be a function there has to be one y fo every x if any x(input) has more than one y(output) it's not a function

3 0

4 years ago

Mr. Shamir employs two part-time typists, Inna and Jim, for his typing needs. Inna charges $15 an hour and can type 6 pages an h

coldgirl [10]

Answer:

The minimum cost would be 480$ when Inna works for 8 hours and Jim works for 20 hours.

Step-by-step explanation:

We are given the following information in the question:

Charges for 1 hour for Inna = $15

Number of pages typed by Inna in 1 hour = 6

Charges for 1 hour for Jim = $18

Number of pages typed by Jim in 1 hour = 8

Let x be the number of hours Inna work and let y be the number of hours Jim work.

Total cost = $15x + 18y$

We have to minimize this cost.

Then, we can write the following inequalities:

$6x + 8y \geq 208\\x \geq 8\\y \geq 8\\$

The corner points as evaluated from graph are: (8,20) and (24,8)

C(8,20) = 480$

C(24,8) = 504$

Hence, the minimum cost would be 480$ when Inna works for 8 hours and Jim works for 20 hours.

The attached image shows the graph.

3 0

3 years ago

- 30 = 12 – 6r<br><br> Pls help

oee [108]

Answer: r = 7

Step-by-step explanation:

Subtract 12 from both sides to isolate the r variable. You have -42 = -6r. Divide both sides by -6 to get r by itself and you get r = 7. Verify by substituting 7 as the r value and solving the equation.

8 0

3 years ago

Read 2 more answers

What tool is used to measure a regular solid?

Nataly_w [17]

A Graduated Cylinder

6 0

3 years ago