Answer:
35 times, or D
Explanation:
A bag contains 5 red marbles, 6 blue marbles, 3 green marbles, 4 black marbles, and 2 yellow marbles. A marble will be drawn from the bag and replaced 100 times. What is a reasonable prediction for the number of times a green or black marble will be drawn?
A quick lesson on probability:
The probability of an event is: (the number of ways what you want can happen) / (total number of outcomes possible). For example, in a coin flip, there is 1 way to get heads, and 2 possible outcomes. Thus, the possiblity of flipping a coin and getting heads is:
(1 way to get heads) / (2 possible outcomes) = 1/2
Then, if we were to flip the coin 100 times, we would expect about 1/2 of the times to be heads, so we should expect heads 50 times.
On to the problem.
There are 3 green marbles and 4 black marbles, so there are 7 ways to draw a green or black marble.
Then, there are 5 + 6 + 3 + 4 + 2 = 20 possible outcomes.
Using the formula to find the probability, substitute the values we just found.
(the number of ways what you want can happen) / (total number of outcomes possible) =
(7 ways to draw a green or black marble) / (20 marbles that can be drawn) = 7/20 chance of getting a green or black marble.
Then, because there is a 7/20 chance of getting what we want, and there are 100 draws, we can say that an we should get green or black
7/20 * 100 = 35 times, or D
Feel free to ask any questions! :)