Answer:
51/4
Step-by-step explanation:
To begin with you have to understand what is the distribution of the random variable. If X represents the point where the bus breaks down. That is correct.
X~ Uniform(0,100)
Then the probability mass function is given as follows.
Now, imagine that the D represents the distance from the break down point to the nearest station. Think about this, the first service station is 20 meters away from city A, and the second station is located 70 meters away from city A then the mid point between 20 and 70 is (70+20)/2 = 45 then we can represent D as follows
Now, as we said before X represents the random variable where the bus breaks down, then we form a new random variable 
, 
is a random variable as well, remember that there is a theorem that says that
![E[Y] = E[D(X)] = \int\limits_{-\infty}^{\infty} D(x) f(x) \,\, dx](https://tex.z-dn.net/?f=E%5BY%5D%20%3D%20E%5BD%28X%29%5D%20%3D%20%5Cint%5Climits_%7B-%5Cinfty%7D%5E%7B%5Cinfty%7D%20D%28x%29%20f%28x%29%20%5C%2C%5C%2C%20dx)
Where 
is the probability mass function of X. Using the information of our problem
![E[Y] = \int\limits_{-\infty}^{\infty} D(x)f(x) dx \\= \frac{1}{100} \bigg[ \int\limits_{0}^{20} x dx +\int\limits_{20}^{45} (x-20) dx +\int\limits_{45}^{70} (70-x) dx +\int\limits_{70}^{100} (x-70) dx \bigg]\\= \frac{51}{4} = 12.75](https://tex.z-dn.net/?f=E%5BY%5D%20%3D%20%5Cint%5Climits_%7B-%5Cinfty%7D%5E%7B%5Cinfty%7D%20%20D%28x%29f%28x%29%20dx%20%5C%5C%3D%20%5Cfrac%7B1%7D%7B100%7D%20%5Cbigg%5B%20%5Cint%5Climits_%7B0%7D%5E%7B20%7D%20x%20dx%20%2B%5Cint%5Climits_%7B20%7D%5E%7B45%7D%20%28x-20%29%20dx%20%2B%5Cint%5Climits_%7B45%7D%5E%7B70%7D%20%2870-x%29%20dx%20%2B%5Cint%5Climits_%7B70%7D%5E%7B100%7D%20%28x-70%29%20dx%20%20%5Cbigg%5D%5C%5C%3D%20%5Cfrac%7B51%7D%7B4%7D%20%3D%2012.75)
Answer:
E. √180
Step-by-step explanation:
Using Pythagoras' theorem
a^2 + b^2 = c^2 (c = hypotenuse, a and b are legs)
a^2 = c^2 - b^2
a^2 = 18^2 - 12^2
a^2 = 324 - 144
a^2 = 180
a = √180
Answer
E. √180
Answer:
X = > 12 because 15 - 3 = 12 and if X was more than 12 it would be wrong.
Step-by-step explanation:
Answer:
$359.42
Step-by-step explanation:
The difference in the investment values can be computed by making use of the formulas for the account balance in each case.
compound interest: A = P(1 +r)^t . . . . interest at rate r compounded annually
simple interst: A = P(1 +rt) . . . . simple interest at rate r
__
The account earning simple interest will have a balance of ...
A = $8000(1 +0.12×3) = $10,880
The account earning compound interest will have a balance of ...
A = $8000(1 +0.12)^3 ≈ $11,239.42
The difference between the two investments is ...
$11,239.42 -10,880 = $359.42
Answer:
B. (8,4)
Step-by-step explanation:
To find the solution of the system, look at where the lines intersect. The intersecting point is (8,4). The solution to the system of equations is (8,4).
