Final answer:
The probability that Daisy picks a white fish is 2/13, which is already in its simplest form.
Step-by-step explanation:
The student asks about the probability of Daisy picking a white fish from her tank, knowing that there are 13 fish in total: 7 blue, 4 orange, and the rest are white. To find the number of white fish, we subtract the known quantities of blue and orange fish from the total: 13 - 7 - 4 = 2 white fish.
Now, to find the probability that Daisy picks a white fish, we use the formula for probability which is the number of favorable outcomes divided by the total number of outcomes. Thus, the probability is 2/13. To put this fraction in its simplest form, we observe that 2 and 13 have no common factors other than 1, so the fraction is already in its simplest form.