I've done these type of questions before, but haven't touched it for a year and I forgot about it.. so can someone recall my memories ?

Question:

Many residents of suburban neighbourhoods own more than one car but consider one of their cars to be the

main family vehicle. The age of these family vehicles can be modelled by a Normal distribution with mean

2 years and standard deviation 6 months.

a) Approximately what percentage of family vehicles is between 1 and 3 years old?

b) What is the standardised value for a family vehicle that is 3 years and 3 months old?

Show working for me, so I understand how it's done! Argh, so frustrating