A jar contains 25 green and 17 purple marbles. A marble is drawn at random.
P(not a 23). Answer 17/42
correct
assuming that what was meant is that the jar contains ONLY green and purple marbles . . .
I think we can say that, but it's also possible that other marbles were not mentioned.
Read Heinlein's Stranger in a Strange Land. One of the characters is a professional observer. He reports exactly what he sees. If you point to a house and ask what color it is, he'd say, "This side is white," making no assumptions about the unseen sides (if any).
To find the probability of not drawing a 23, we need to first find the total number of marbles in the jar. The given information states that there are 25 green and 17 purple marbles, so the total number of marbles is the sum of these two quantities:
Total marbles = Number of green marbles + Number of purple marbles
Total marbles = 25 + 17 = 42
Since the probability of an event happening is given by the number of desirable outcomes divided by the number of possible outcomes, we can now calculate the probability of not drawing a 23.
Number of desirable outcomes (not drawing 23) = Total number of marbles - Number of 23 marbles
Number of desirable outcomes = 42 - 1 = 41
Number of possible outcomes = Total number of marbles
Now, we can find the probability by dividing the number of desirable outcomes by the number of possible outcomes:
P(not a 23) = Number of desirable outcomes / Number of possible outcomes
P(not a 23) = 41 / 42
So, the probability of not drawing a 23 is 41/42 or approximately 0.9762.