1) Suppose the cumulative distribution function of the random variable X is
f(x) =
| 0 |
x < 0 |
| 0.2x |
0 < x < 5 |
| 1 |
5 < x |
Determine the following:
(a) P(X < 2.8)
2) the compressive strength of samples of cement can be modeled by a normal distribution with a mean of 6000 kilograms per square centimeter and a standard deviation of 100 kilograms per square centimeter.
(a) What is the probability that a sample's strength is less than 6250 Kg/cm2? (Round your answer to 5 decimal places.)
3) The manufacturing of semiconductor chips produces 2% defective chips. Assume the chips are independent and that a lot contains 1000 chips.
(Round your answers to 4 decimal places.)
(a) Approximate the probability that more than 25 are defective.