1) Compressive strength of samples of cement can be modeled by the normal distribution with the mean of 6000 kilograms per square centimeter and standard deviation of 100 kilograms per square centimeter.
i) What strength is exceeded by 95% of samples?
2) Manufacturing of semiconductor chips makes 2% defective chips. Suppose chips are independent and that the lot has 1000 chips.
i) Estimate probability that between 20 and 30 chips are defective.