Answer:
Step-by-step explanation:
81x² - 6x
Given:
Per month fee = $55
One-time recital fee = $165
The equation represents the $495 total cost that Barbara paid to Dance Unlimited.

To find:
We need to find the number of month Barbara receive dance lessons from Dance Unlimited.
Solution:
We have,

Here, m is number of months. We need to isolate m.
Subtract 165 from both sides.


Divide both sides by 55.


The value of m is 6. So, the required number of month Barbara receive dance lessons from Dance Unlimited is 6.
Solution :
Group Before After
Mean 693.75 743.75
Sd 155.37 143.92
SEM 54.93 50.88
n 8 8
Null hypothesis : The preparation course not effective.

Alternative hypothesis : The preparation course is effective in improving the exam scores.
(after - before)