solve if you can?

Solve any three sub questions from the following : Which two types of account can you open in a bank?

Can you hear your own words if you are standing in a perfect vacuum ? Can you hear your, friend in the same conditions ?

Can You Solve This || Answer Is Unpredictable || (7+sqrt50)^(1/3) - (7-sqrt50)^(1/3)

A can solve 75% of the problems in a book on mathematics and B can solve 70%. What is the probability that a problem chosen at random is solved?

The probability that A can solve a problem is 2//3 and B can solve it is 3//4 . If both attempt the problem, what is the probability that the problem gets solved ?