Answer:
The probability that a randomly selected call time will be less than 30 seconds is 0.7443.
Step-by-step explanation:
We are given that the caller times at a customer service center has an exponential distribution with an average of 22 seconds.
Let X = caller times at a customer service center
The probability distribution (pdf) of the exponential distribution is given by;

Here,
= exponential parameter
Now, the mean of the exponential distribution is given by;
Mean =
So,
⇒
SO, X ~ Exp(
)
To find the given probability we will use cumulative distribution function (cdf) of the exponential distribution, i.e;
; x > 0
Now, the probability that a randomly selected call time will be less than 30 seconds is given by = P(X < 30 seconds)
P(X < 30) =
= 1 - 0.2557
= 0.7443
First let's talk about the blue line.
You can see its rising so its slope is certainly positive. But by how much is it rising? You can observe that each unit it rises it goes 1 forward and 1 up so its slope is the ratio of 1 up and 1 forward which is just 1.
We have thusly,

Now look at where blue line intercepts y-axis, -1. That is our n.
So the blue line has the equation of,

Next the black lines. The black lines are axes so their equations are a bit different.
First let's deal with x-axis, does it have slope? Yes but it is 0. The x-axis is still, not rising nor falling. Where does x-axis intercept y-axis? At 0. So the equation would be,

Now we have y-axis. Does y axis have a slope? Yes but it is
. The y-axis rises infinitely in no run. Where does it intercept y-axis? Everywhere! So what should the equation be? What if we ask where does y-axis intercept x-axis and write its equation in terms of x. Y-axis intercepts x-axis at 0 which means its equation is,

That is, every point of a form
lies on y-axis.
Hope this helps :)
Questions:
(a) What is a simplified expression for (x + y) – (x – y)?
(b) Carlotta thinks that
is the same as
. Which statement shows that it is NOT the same?
Answer:


Step-by-step explanation:
Solving (a):
Given

Required
Simplify

Open brackets

Collect Like Terms



Solving (b):
Given
and 
Required
Which expression shows they are not the same
The expression that shows this is:

Take for instance; y=2
Substitute 2 for y in 

Evaluate all exponents



The above expression supports 
I think d but i might be wrong :( sorry