When you go into this problem, you want to figure out your marble ammount to 50 so in this case we will say C for color and 50 for the total ammount of marbles.
We know 15 are pink, 8 are black, 2 are green, 18 are clear, and 7 are striped
15P/50
8B/50
2G/50
18C/50
7S/50 for a total of 50 marbles
Now we use the chart to decide our awnsers
A. We know our propability of drawing a green and clear is 20/50 which if we simplify is a 2/5 ratio. If We put this in perspective 2/5 is rare and is unlikley to even.
B. We know a striped marble is 18/50 or 1.8/5 ratio which is mainly unlikely
C. We have 23/50 marbles that are black and pink, our propability is about 2.3/5 and gives us an even chance to get one of these
D. We know we have 33/50 marbles that are pink and clear and gives us a 3.3/5 chance of getting one of these and gives us an even to likely chance of getting one of these.
E. If we have a total of 17 marbles in these 3 colors, we have a 1.7/5 chance of getting one of these and is probably impossible to unlikey.