Adult raccoon tail lengths of a certain species are normally distributed with mean 28 cm and standard deviation 3.3 cm.

(a) Find the probability that a randomly chosen adult raccoon has a tail length between 23 and 35 cm. [4]

Adult raccoon masses of the same species are normally distributed with mean 8.5 kg and standard deviation \(\sigma\) kg. 75% have mass greater than 7.6 kg.

(b) Find \(\sigma\). [3]