To find the odds of choosing a red marble from the bag, we first need to count the total number of marbles and the number of red marbles.
In the bag, we have:
- 2 blue marbles
- 1 green marble
- 4 red marbles
Total number of marbles = 2 (blue) + 1 (green) + 4 (red) = 7 marbles.
The number of red marbles = 4.
The odds of choosing a red marble can be expressed as the ratio of the number of favorable outcomes (choosing a red marble) to the number of unfavorable outcomes (choosing a marble that is not red).
Number of favorable outcomes (red marbles) = 4
Number of unfavorable outcomes (non-red marbles) = Total marbles - Red marbles = 7 - 4 = 3
Thus, the odds of choosing a red marble are:
- Odds of red = Number of favorable outcomes : Number of unfavorable outcomes = 4 : 3.
So, the answer is A. 4:3.