Integers are only whole numbers, so numbers that are not fractions or decimals, so for example lets say that Jerry has 3 and 1/2 cookies, and he thought about his math lesson in school today, ( Integers ) Well since he does not have just whole numbers, like -2, or 7, he has just a mixed number amount of cookies. So basically I'm saying that as long as they aren't fractions, or decimals they are integers. So -6.06 is not an integer.
Since 12 out of 30 marbles were black, you can assume that the percentage of black marbles in the bag is 40% (Ex: 12/30=.4) The probability that the marble you pick is black is equal to the percentage of black marbles in the bag. 40% is equal to 2/5.
