A bag contains 30 marbles, 3 of which are blue, 20 are red, 5 are green, and 2 are purple. Emerson takes a marble out of the bag, records the color, and returns it to the bag. How many purple marbles should he expect after 300 trials? 20
30
50
200

but about 20. 2 x 10 since there are 30 marbles, so it makes sense to say 30 x 10 to get 300, but since you only have 2 purple, you only get 2 purple out of every 30,  

SO in conclusion, 20 purple marbles.

Explanation:

porter is writing economic history because he is focusing on the cost of developing vaccines.

deflation   hope this