Answer:
a) P(t>3)=0.30
b) P(t>10|t>9)=0.67
Step-by-step explanation:
We have a repair time modeled as an exponentially random variable, with mean 1/0.4=2.5 hours.
The parameter λ of the exponential distribution is the inverse of the mean, so its λ=0.4 h^-1.
The probabity that a repair time exceeds k hours can be written as:

(a) the probability that a repair time exceeds 3 hours?

(b) the conditional probability that a repair takes at least 10 hours, given that it takes more than 9 hours?
The exponential distribution has a memoryless property, in which the probabilities of future events are not dependant of past events.
In this case, the conditional probability that a repair takes at least 10 hours, given that it takes more than 9 hours is equal to the probability that a repair takes at least (10-9)=1 hour.


The value of x
5x+15+17(sides)=45(perimeter of sides/sum of sides)
5x+32=45
5x=45-32
5x=13
x=13/5
x=2.6
The value of x is 2.6
36 and 48 have the ratio of 3:4
Answer:
-1 <= x <= 1
Step-by-step explanation:
√((1-2x+x^2)+2-2x^2)
= √((1-x)^2 + 2*(1-x)(1+x) )
điều kiện là 1 - x > =0 và 1+x >=0
giải 2 bất phương trình trên ta thu đc kết ququả
There are two methods to solve this problem. One of them is the typical method and the other one is the short-cut. I will explain the shortcut
Short-cut:
This method is quick and easy, and works with ALL triangles, which is why I suggest you use this. You make proportions. Since the triangles are similar, we can use CPCTC. Thereafter,

Now, you just need to identify the terms, substitute, and solve for the unknown, which would be k.

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So we found k, but it is asking for BE. Therefore, plug in the value of k, which is 11, into the expression for BE, which is k-7.
BE=K-7
k=11
BE=11-7
BE=4
Your answer is 4.