hello can someone please help me the question's below. i have the answers to question, but i just cannot figure out how they got the answer. I referred to my textbook for help but still was confused.

1. An athlete believes that her times for running 200 metres in races are normally distributed

with a mean of 22.8 seconds.

(a) Given that her time is over 23.3 seconds in 20% of her races, calculate the variance of

her times.

(5 marks)

(b) The record over this distance for women at her club is 21.82 seconds. According to her

model, what is the chance that she will beat this record in her next race?

(3 marks)

Any help is appreichated

Thank You

Kind Regards