You choose 4 newspapers from 3+4+2=9 newspapers on the rack in total, which means you need to find the number of possible combinations (choose r objects from set of n objects), where r=4, n=9.
The formula for calculating the number of possible combinations is:
n!/(r!*(n-r)!)
The total number of ways to choose 4 newspapers form 9 is C(9,4) = 9*8*7*6*5 / 4! =15120/24=630
1. The probability that you choose 1 issue of Sports Illustrated and 3 issues of Time is:
(C(3,1)*C(4,3))/C(9,4)
C(3,1)=3!/1!*2!=3
C(4,3)=4!/1!*1!=24
3*24/630=72/630=0.114
2. The probability that you choose at least 1 of the Time magazines is:
1- the probability that you choose no Time magazine
1-C(4,0)*3/9^0*(1-3/9)^4
1-*0.33^4=1-0.011
0.989