Answer:
4/5
Step-by-step explanation:
Andrew has just two possibilities: pulling out a white sock or pulling out a black sock.
If the probability of Andrew pulling out a black sock is 1/5, knowing that the sum of both probabilities need to be 1, we can calculate the probability of pulling out a white sock if the following equations:
Prob_white + Prob_black = 1
Prob_black = 1/5
So:
Prob_white + 1/5 = 1
Prob_white = 1 - 1/5 = 4/5
The probability of Andrew pulling out a white sock is 4/5.
