help me on this one

QUESTION 1 The probability that a certain type of chip will fail after installation is 0-15. A memory board for a computer contains 5 such chips. The operation will be satisfactory if two or more of the chips on the board do not fail. a} What is the probability that a memory board operates satisfactorily? (3 marks} b) Ifthere are six such memory boards in each computer, what is the probability that ve of them operate satisfactorily? (2 marks} c) Find the probability that the seventh chips installed is the third chip that fails aer installation. (2 marks)