The expenditure on titbits by primary school students is normally distributed with a mean of $1.40 and population standard deviation of $0.36. The titbits stall owner takes a random sample of 144 students to estimate the mean.

(a)What is the probability that sample mean exceeds $1.60? (0)

(b)What is the probability that sample mean is between $1.30 and $1.50? (0.9992)

(c)Find the probability in percentage terms that a randomly selected student will spend between $1.40 and $1.60 on titbits. (21.23%)