Answer:
The test statistics is
Step-by-step explanation:
From the question we are told that
The sample size is n = 100
The null hypothesis is 
The alternative hypothesis is 
The sample mean is 
The standard deviation is 
The level of significance is 
Generally the test statistics is mathematically represented as

=> 
=>
Answer:
It's a simultaneous equation because it as two solution
Step-by-step explanation:
For y=4 draw a horizontal line through the y-axis at point (0,4). Y-axis is the vertical.
For x=-3 draw a vertical line through the x-axis at point (-3,0). X-axis is the horizontal.
The shirts were sold at $15 each.
8.83176088663 is the answer