15. A jar contains 6 red marbles, 4 blue marbles, and 10 green marbles. If a marble is selected at random from the jar, which of the following is the probability that it is not red?
Answer: B
The probability that a randomly selected marble is not red is 7/10.
To find the probability that a marble drawn from the jar is not red, we first determine the total number of marbles, which is 20 (6 red + 4 blue + 10 green). The number of marbles that are not red is 14 (4 blue + 10 green), leading to a probability of 14 out of 20, which simplifies to 7/10.
A) 3/10
This option represents a probability that suggests only 3 out of 10 marbles are not red, which is incorrect. Since there are 14 non-red marbles in the jar, this probability does not reflect the actual number of non-red marbles available.
B) 7/10
This option correctly represents the probability of selecting a marble that is not red. With 14 non-red marbles out of 20 total marbles, the probability is accurately calculated as 14/20, which simplifies to 7/10.
C) 1/5
This option indicates a probability of 1 out of 5 marbles being non-red, which is incorrect. Given that there are 14 non-red marbles out of a total of 20, this choice does not accurately represent the proportions in the jar.
D) 1/2
This option suggests that half of the marbles are not red, which is also incorrect. With 14 out of 20 marbles being non-red, the correct probability far exceeds 1/2, making this choice invalid.
Conclusion
The correct probability that a marble selected at random from the jar is not red is 7/10, as it accurately reflects the ratio of non-red marbles to the total number of marbles. All other options fail to represent the true distribution of marbles, making them incorrect in this context.