Using the percentage concept, it is found that 25% of 6th graders are involved in the yearbook club.
<h3>What is a percentage?</h3>
The percentage of an amount a over a total amount b is given by a multiplied by 100% and divided by b, that is:

In this problem, 10 out of 10 + 24 + 6 = 40 6th graders are involved in the yearbook club, hence the corresponding percentage is given by:

More can be learned about percentages at brainly.com/question/10491646
I think there are no potential bias since expect for when the test subjects were selected. There is no mention of how the subjects were selected. This could result to lurking variables which are is the hereditary susceptibility to tumors and congenital conditions of the mice that might be in the form of tumors already present in the mice's bodies.
Answer:
Step-by-step explanation:
B = 2/5(A - 9)
(5/2)B = A - 9
A = 9 + (5/2)B