What did I do wrong here?
1 answer:
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Answer:
a) E(X)=1
b) σ=1
c) P(X>1)=0.368
d) P(2<X<5)=0.128
Step-by-step explanation:
We have X: "the time between two successive arrivals at the drive-up window of a local bank", exponentially distributed with λ = 1.
a) We have to compute the expected time between two successive arrivals.
The expected value for X as it is exponentially distributed is:
b) We have to compute the standard deviation of X.
The standard deviation is calculated as:
c) The probability that X is larger than 1 (P(X>1))
We can express the probability as:
d) The probability that X is between 2 and 5 (P(2<X<5))
Step-by-step explanation:
x^3 is a perfect cube, 8 is a perfect cube, so we use difference of cubes.
Cube root of x^3 is x.
Cube root of 8 is 2
So
a=x
b= 2.
Set these equations equal to zero
If we do the discriminant, we get a negative answer so we would have two imaginary solutions,
Thus the only real root is 2.
If you want imaginary solutions, apply the quadratic formula.
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