Question: The resistance for resistors of a certain type is a random variable X having the normal distribution with mean 9 ohms and standard deviation 0.4 ohms. A resistor is acceptable if its resistance is between 8.6 and 9.8 ohms.
(a) What is the probability that a randomly chosen resistor is acceptable?
(b) What is the probability that out of four randomly and independently selected resistors, two are acceptable?