need help with this

a) The average monthly mortgage payment for all homeowners in a city is RM2850. Suppose that the distribution of monthly mortgages paid by homeowners in this city follow an approximate normal distribution with a mean of RM2850 and a standard deviation of RM420, Find the probability that the monthly mortgage paid by a randomly selected homeowner from this city is less than RM1200 il between RM2300 and RM3140 Il more than RM3600 iv. between RM3200 and RM3700 (2 Marks) (2 Marks) (2 Marks) (2 Marks) b) Determine the value of z so that the area under the standard normal curve (1 Mark) (1 Mark) I. in the right tail is .0500 il in the left tail is .0250 [Total: 10 Marks]