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1 year ago

X = 11 + 2 (__) X = 1 + _X = _______

Mathematics

1 answer:

Sloan [31]1 year ago

4 0

Answer:

Step-by-step explanation:

I'm not sure about it

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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

2 years ago

8ft=how many yards and feet 68in=how many ft and in 3,520y=how many miles

Nataly_w [17]

8ft = 2yrds and 2 feet
68in= 5ft and 8in
I don't know the last one XD

3 0

2 years ago

What is the value of the expression as a mixed number 15/8 + 1/4

Oksanka [162]

15/8 + 1/4

15/8 + 2/8

= (15 + 2) /8

= 17/8

= 2 1/8. 2 whole number 1/8.

5 0

2 years ago

A total of 579 tickets were sold for the school play they were either adult tickets or student tickets. there were 71 fewer stud

stepan [7]

Answer: 325

Step-by-step explanation:

Student tickets: x

Adult tickets: x + 71

Total: 579

x + x + 71 = 579

2x + 71 = 579

2x = 579 - 71

2x = 508

x = 508/2

x = 254

Adult tickets = x + 71 = 254 + 71 = 325

P.S. Hope it helps. If you have any questions, feel free to ask them here. I'll be happy to help! Have a wonderful day!

4 0

1 year ago

Point p is the midpoint of de dp 6x+4 and de = 14x -10

vfiekz [6]

Answer:

x = 9

Step-by-step explanation:

A midpoint is found by adding up two numbers and then dividing by 2 (Also known as an average). Therefore, a midpoint marks half of a line. That means that DP is 1/2 of DE. We can now form an equation. 6x + 4 = 1/2 * (14x - 10), making 6x + 4 = 7x - 5 by using the distributive property. Next, isolate x by subtracting by 6x on both sides and adding by 5 on both sides. You would get x = 5 + 4, which means that x = 9.

3 0

2 years ago

X = 11 + 2 (______) X = 1 + _________X = ___________ ​

X = 11 + 2 (__) X = 1 + _X = _______