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**isuckatprobability** Problem: A material is known for 20% breakage under stress. Five different samples of such materials are tested.

A. What is the probability that the third sample resists the stress?

Mr F says: 4/5

B. What is the probability that the third and fourth samples resist the stress?

Mr F says: (4/5)^2

I don't know how to approach this question. I see that 1 material are damaged for every 5 tested, and I was thinking of using the binomial distribution for it. But I don't think I can, because I believe that distribution involves multiple. Can someone give me some direction to go with this?