The daily mobile data usage of Alvin and Barbara are independently and normally distributed. The average and standard deviation of Alvin's data usage are 30 MB and 16 MB respectively while the average and standard deviation of Barbara's data usage are 25 MB and 12 MB respectively. Calculate the probability for

1.Alvin use more than 45 MB and Barbara use less than 31 MB.

2.Alvin use more than 45 MB or Barbara use less than 31 MB.

3.Alvin use less than 50 MB when Barbara use more than 36 MB.

4.Alvin use less than 30 MB but more than 50 MB.

5.Alvin and Barbara's total usage is between 60 MB and 72 MB.