1. 1000 bits are independently transmitted from a source to a sink. The probability of a faulty transmission of a bit is 0.0005. What is the probability that the transmission of at least two bits is not successful ?
2. To construct a circuit a student needs, among others, 12 chips of a certain type. The student knows that 4% of these chips are defective. How many chips have to be provided so that, with a probability of not less than 0.9, the student has a sufficient number of nondefective chips in order to be able to construct the circuit ?