Answer:
The shape and rate parameters are
and
.
Step-by-step explanation:
Let <em>X</em> = service time for each individual.
The average service time is, <em>β</em> = 12 minutes.
The random variable follows an Exponential distribution with parameter,
.
The service time for the next 3 customers is,
<em>Z</em> = <em>X</em>₁ + <em>X</em>₂ + <em>X</em>₃
All the <em>X</em>
's are independent Exponential random variable.
The sum of independent Exponential random variables is known as a Gamma or Erlang random variable.
The random variable <em>Z</em> follows a Gamma distribution with parameters (<em>α</em>, <em>n</em>).
The parameters are:

Thus, the shape and rate parameters are
and
.
First, multiply the top equation by 2 and bottom by -3.
60x+60y=900
-60x-75y=-1035
————————
-15y=-135
—————-
-15=-15
y=9
So the answer should be 9.
The simplest form of an interest equation is A = P(1+rt)
where A = the total amount of money at the end, P = the principal (or amount of money you started with), r = the rate in percent, and t = the time in years.
In this case, P = 15000, r = 0.03 (because 3% in decimal form is 0.03), and t = 1:

So, after 1 year he will get $15450 back, making him $450 more.