Tyre pressures on a certain type of car independently follow a normal distribution with mean 1.9 bars and standard deviation 0.15 bars.
(i) Find the probability that all four tyres on a car of this type have pressures between 1.82 bars and 1.92 bars.
(ii) Safety regulations state that the pressures must be between 1.9−b bars and 1.9+b bars. It is known that 80% of tyres are within these safety limits. Find the safety limits
Find out how.