Probability and normal distribution

[Guest]

Hi everyone please provide me the solution for the following problems on probability.Also please give me the valid and good explanation for the how you are arriving to the answers.Actually i am not finding good explanation for these problems in the book.

Q1)
The table below shows the distribution of a group of 40 college students by gender and class

Sex Sophomore Junior Senior
---------------------------------
M 6 10 2
F 10 9 3
---------------------------------
If one student is selected from this group ,find the probability that the student chosen is female or sophomore.

Q2)

If an integer is readonly selected from all two 2-digit integer w.i.p that integer chosen has at least 4 in 10th place or unit place

Q3)
A random variable Y is normally distributed witha a mean of 200 & a standard deviation of 10

Qty A or Qty B
Probability 1/6
of the event
that the value of
Y is greater than
220

Thanks,
S.