another probability question

another fun question i have to work on. so ive drawn a little tree and leaf diagram, 0.54 (read email, talk on phone) and 0.46 (dont read mail, talk on phone). coming off the 0.54 stem, 0.20 (write to-do lists) and 0.80 (dont write to-do lists). i guess i should be doing a matrix but not sure on how to do it.


According to a survey published by ComPsych Corporation, 54% of all workers read e-mail while they are talking on the phone. Suppose that 20% of those who read e-mail while they are talking on the phone write personal "to-do" lists during meetings. Assuming that these figures are true for all workers, if a worker is randomly selected, determine the following probabilities:

Round your answers to 3 decimal places.

a. The worker reads e-mail while talking on the phone and writes personal "to-do" lists during meetings.

i guess its just 0.54 x 0.20 = 0.108 ?

b. The worker does not write personal "to-do" lists given that he reads e-mail while talking on the phone.

(sounds conditional)

c.The worker does not write personal "to-do" lists and does read e-mail while talking on the phone.

(looks similar to 'b' but says "and" instead of "given" so i guess thats the point.)

help please. :?