Step-by-step explanation:

15 - c = 6
15 - 6 = c
9 = c
c = 9
Answer:
The number generator is not fair. In most of the experiments, considerably less than 60% of the selected marbles are green.
Step-by-step explanation:
Run a significant number of times, a fair distribution should be a bell curve centered on the 6 for 60%
Answer:
a = -4.
Step-by-step explanation:
25(√5)^a * (√5) ^3 = 5√5
25*5^a/2 * 5^3/2 = 5*5^1/2
25*5^a/2 = 5*5^1/2 / 5^3/2
25*5^a/2 = 5^1 *5^1/2 / 5^3/2
25*5^a/2 = 5^3/2 / 5^3/2 = 1
5^a/2 = 1/25 = 5^-2
The bases are equal, so
a/2 = -2
a = -4.