A box contains 6 red balls, 4 blue balls, and 5 green balls. If one ball is randomly selected from the box, what is the probability of choosing a red ball?
A) 6/15
B) 4/15
C) 2/5
D) 3/7
E) 6/15
Answer: A) 6/15
Explanation:
The total number of balls in the box is 6 (red) + 4 (blue) + 5 (green) = 15 balls.
To find the probability of choosing a red ball, divide the number of red balls by the total number of balls:
Probability of choosing a red ball = Number of red balls / Total number of balls
Probability of choosing a red ball = 6 / 15
Simplify the fraction:
Probability of choosing a red ball = 2 / 5
Therefore, the correct answer is A) 6/15.
Question #2
In a bag, there are 5 red marbles, 4 blue marbles, and 6 green marbles. Two marbles are drawn at random from the bag without replacement. What is the probability of drawing one red marble and one blue marble, in any order?
A) 5/33
B) 2/15
C) 1/3
D) 20/63
E) 2/7
Answer: D) 20/63
Explanation:
To find the probability of drawing one red marble and one blue marble, in any order, we can consider two scenarios:
Scenario 1: Red then Blue
Scenario 2: Blue then Red
Let's calculate the probability for each scenario:
Scenario 1: Red then Blue
Probability of drawing a red marble first: *(5 red marbles) / (15 total marbles) = 5/15*
Probability of drawing a blue marble second (after removing one red marble): *(4 blue marbles) / (14 remaining marbles) = 4/14*
Scenario 2: Blue then Red
Probability of drawing a blue marble first: (4 blue marbles) / (15 total marbles) = 4/15
Probability of drawing a red marble second (after removing one blue marble): (5 red marbles) / (14 remaining marbles) = 5/14
Now, add the probabilities from both scenarios to get the total probability:
Total probability = Probability of Scenario 1 + Probability of Scenario 2
Total probability = (5/15) * (4/14) + (4/15) * (5/14)
Total probability = 20/210 + 20/210
Total probability = 40/210
Total probability = 20/105
Total probability = 4/21
Therefore, the probability of drawing one red marble and one blue marble, in any order, is 20/63.