Answer:
im pretty sure its -4
Step-by-step explanation:
you cant really hold me to it but its -1/4 or -4
Answer:
B is the correct answer
Kevin is K
Daniel is D
Now: K
K = D + 3
3 years ago:
K - 2 = 4(d - 2)
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Answer:
624.5 feet
Step-by-step explanation:
Calculation to determine how many feet from the boat is the parasailor
Based on the information given we would make use of Pythagorean theorem to determine how many feet from the boat is the parasailor using this formula
a²+b²=c²
First step is to plug in the formula by substituting the given value
500²+b²=800²
Second step is to evaluate the exponent
250,000+b²=640,000
Third step is to substract 250,000 from both side and simplify
250,000+b²-250,000=640,000-250,000
b²=390,000
Now let determine how many feet from the boat is the parasailor
Parasailor feet=√b²
Parasailor feet=√390,000
Parasailor feet=b=624.49
Parasailor feet=b=624.5 feet (Approximately)
Therefore how many feet from the boat is the parasailor will be 624.5 feet
Adding 2 to each value of the random variable
makes a new random variable
. Its mean would be
![E[X+2]=E[X]+E[2]=E[X]+2](https://tex.z-dn.net/?f=E%5BX%2B2%5D%3DE%5BX%5D%2BE%5B2%5D%3DE%5BX%5D%2B2)
since expectation is linear, and the expected value of a constant is that constant.
is the mean of
, so the new mean would be
![E[X+2]=10+2=12](https://tex.z-dn.net/?f=E%5BX%2B2%5D%3D10%2B2%3D12)
The variance of a random variable
is
![V[X]=E[X^2]-E[X]^2](https://tex.z-dn.net/?f=V%5BX%5D%3DE%5BX%5E2%5D-E%5BX%5D%5E2)
so the variance of
would be
![V[X+2]=E[(X+2)^2]-E[X+2]^2](https://tex.z-dn.net/?f=V%5BX%2B2%5D%3DE%5B%28X%2B2%29%5E2%5D-E%5BX%2B2%5D%5E2)
We already know
, so simplifying above, we get
![V[X+2]=E[X^2+4X+4]-12^2](https://tex.z-dn.net/?f=V%5BX%2B2%5D%3DE%5BX%5E2%2B4X%2B4%5D-12%5E2)
![V[X+2]=E[X^2]+4E[X]+4-12^2](https://tex.z-dn.net/?f=V%5BX%2B2%5D%3DE%5BX%5E2%5D%2B4E%5BX%5D%2B4-12%5E2)
![V[X+2]=(V[X]+E[X]^2)+4E[X]-140](https://tex.z-dn.net/?f=V%5BX%2B2%5D%3D%28V%5BX%5D%2BE%5BX%5D%5E2%29%2B4E%5BX%5D-140)
Standard deviation is the square root of variance, so
.
![\implies V[X+2]=(9+10^2)+4(10)-140=9](https://tex.z-dn.net/?f=%5Cimplies%20V%5BX%2B2%5D%3D%289%2B10%5E2%29%2B4%2810%29-140%3D9)
so the standard deviation remains unchanged at 3.
NB: More generally, the variance of
for
is
![V[aX+b]=a^2V[X]+b^2V[1]](https://tex.z-dn.net/?f=V%5BaX%2Bb%5D%3Da%5E2V%5BX%5D%2Bb%5E2V%5B1%5D)
but the variance of a constant is 0. In this case,
, so we're left with
, as expected.