Given that a specimen has an additive concentration of .04, what is the probability that it's strength is 150 or more?
use the formula
A : the event that it has a strength of 150 or more
B : the event that it has an addative concentration of 0.04
You can read P(A and B) from the table, and you can get P(B) from the marginal distribution.
Find µx and µy.
I assume this refers to the population mean of your two variables.
You said you already have the marginal distributions. Use the marginal distributions for each variable and the formula:
Post your solution up to the point you are stuck if you need more help