A can solve 90% of the problems given in a book and B can solve 70%. What is the probability that  at least one of them will solve the problem, selected at random from the book?

Explanation

Let `E` and `F` be the events defined as follows:


`E=A` solves the problem


`F=B` solves the problem


Clearly, `E` and `F` are independent events such that


`P(E)=frac{90}{100}=frac{9}{10}`


And, `P(F)=frac{70}{100}=frac{7}{10}`

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