Hello tutors, can I please get you assistance with the following ? Thank You so much

Psychobehavioral experts have calculated that the attention span (Y) of a student randomly chosen from the population we are talking about is represented by the following function:

= 3²+4

a) What is the expected attention span?

Another psychologist, using a different instrument, measures attention span according to the following formula:

Y= 3X + 4

b)What is the variance of the attention span, according to this other psychologist?