Answer:
The value of the test statistic is 
Step-by-step explanation:
The null hypothesis is:

The alternate hypotesis is:

Our test statistic is:

In which X is the sample mean,
is the null hypothesis value,
is the standard deviation and n is the size of the sample.
In this problem:

So



The value of the test statistic is 
Adding the two equations
3x + 6y + 3x - 6y = 36+0
6x = 36
x = 6
.
subtracting second equation from first
(3x + 6y ) - (3x-6y) =36 -0
12y = 36
y = 3
.
therefore
x = 6 and y = 3
(6,3)
7x + 15 = 1520
It’s $7 times the unknown number of shirts (x). Plus $15 to ship. All has to equal the total of $1,520.
The time it will take the principal to grow to the desired amount is 0.7 years
Using the compound interest formula :
A = P(1 + r/n)^(nt)
A = final amount = 225,000
P = principal = 180,000
r = rate = 3.12%
n = Number of compounding times per period = 12(monthly)
t = time
225000 = 180000(1 + (0.0312 /12))^(12t)
Divide both sides by 180000
225000/180000 = (1 + (0.0312 /12))^(12t)
1.25 = 1.026^12t
Take the log of both sides
0.0969100 = 0.0111473 × 12t
0.0969100 = 0.1337676t
Divide both sides by 0.1337676 to isolate t
0.0969100 / 0.1337676 = t
0.7244 years
0.7 years
It will take 0.7 years for the amount to grow
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