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2 years ago

The following two-way table shows the number of students of a school who have a video game and/or have a laptop:

Mathematics

2 answers:

zzz [600]2 years ago

6 0

It's 15 because it falls on the graph between people who have computers and have video games

mote1985 [20]2 years ago

5 0

Its 65 because 15 + 50 =65

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A box contains 5 red and 5 blue marbles. Two marbles are withdrawn randomly. If they are the same color, then you win $1.10; if

topjm [15]

Answer:

a) The expected value is $\frac{-1}{15}$

b) The variance is $\frac{49}{45}$

Step-by-step explanation:

We can assume that both marbles are withdrawn at the same time. We will define the probability as follows

#events of interest/total number of events.

We have 10 marbles in total. The number of different ways in which we can withdrawn 2 marbles out of 10 is $\binom{10}{2}$ .

Consider the case in which we choose two of the same color. That is, out of 5, we pick 2. The different ways of choosing 2 out of 5 is $\binom{5}{2}$ . Since we have 2 colors, we can either choose 2 of them blue or 2 of the red, so the total number of ways of choosing is just the double.

Consider the case in which we choose one of each color. Then, out of 5 we pick 1. So, the total number of ways in which we pick 1 of each color is $\binom{5}{1}\cdot \binom{5}{1}$ . So, we define the following probabilities.

Probability of winning: $\frac{2\binom{5}{2}}{\binom{10}{2}}= \frac{4}{9}$

Probability of losing $\frac{(\binom{5}{1})^2}{\binom{10}{2}}\frac{5}{9}$

Let X be the expected value of the amount you can win. Then,

E(X) = 1.10*probability of winning - 1 probability of losing = $1.10\cdot \frac{4}{9}-\frac{5}{9}=\frac{-1}{15}$

Consider the expected value of the square of the amount you can win, Then

E(X^2) = (1.10^2)*probability of winning + probability of losing = $1.10^2\cdot \frac{4}{9}+\frac{5}{9}=\frac{82}{75}$

We will use the following formula

$Var(X) = E(X^2)-E(X)^2$

Thus

Var(X) = $\frac{82}{75}-(\frac{-1}{15})^2 = \frac{49}{45}$

7 0

3 years ago

1/6 divided by 4 i need the answer please thank you.

TiliK225 [7]

Answer:

The correct answer is 1/24

I'm 100000000000% sure.

5 0

2 years ago

Read 2 more answers

Dad is 4 times as old as his son Jim. In 10 years, Dad's age will be 20 years more than twice Jim's age. How old is Jim? 10 year

mezya [45]

Jim is currently 15 years old!!

8 0

2 years ago

Someone please help me will give brainliest!!!!!

ololo11 [35]

I believe the fastest way to solve this problem is to take any two of the given points and to find the slope and y-intercept of the line connecting those two points.

Let's choose the 2 given points (-3,16) and (-1,12).
Going from the first point to the second, the increase in x is 2 and the increase in y is actually a decrease: -4. Thus, the slope of the line connecting these two points is m = -4/2, or m = -2.

Now use the slope-intercept formula to find the y-intercept, b.

One point on the line is (-3,16), and the slope is m = -2.

Thus, the slope-intercept formula y = mx + b becomes 16 = -2(-3) + b.
Here, b comes out to 10.

So now we have the slope and the y-intercept. Write the equation:

y = mx + b becomes y=-2x+10. Which of the four given answer choices is the correct one?

3 0

2 years ago

I don't know what the answer is to divide 180 in a ratio of 4:5:9

Karolina [17]

Hello there,

First you need to add together the numbers.
4+5+9 = 18
Divide the total by this,
180 / 18 = 10
Multiply each number by 10.
40:50:90.

Hope This Helps You!
Good Luck Studying :)

4 0

3 years ago

Read 2 more answers