A bag consists of 20 marbles, of which 5 are blue, 9 are red, and the remainder are white. If Lisa is to select a marble from the bag at random, what is the probability that the marble will be red or white?
A. 3/4
B. 1/2
C. 1/4
D. 1/8
E. 1/16
The OA is A.
So, white = 20 - 5 - 9 = 6.
The probability that the marble will be red or white = probability that the marble will be red + probability that the marble will be white.
Probability that the marble will be red or white = 9/20+6/20 = 15/20 = 3/4.
Has anyone another suggestion about how to solve this PS question? Thanks in advance.
A bag consists of 20 marbles, of which 5 are blue, 9 are red
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Your solution is perfect.BTGmoderatorLU wrote:A bag consists of 20 marbles, of which 5 are blue, 9 are red, and the remainder are white. If Lisa is to select a marble from the bag at random, what is the probability that the marble will be red or white?
A. 3/4
B. 1/2
C. 1/4
D. 1/8
E. 1/16
The OA is A.
So, white = 20 - 5 - 9 = 6.
The probability that the marble will be red or white = probability that the marble will be red + probability that the marble will be white.
Probability that the marble will be red or white = 9/20+6/20 = 15/20 = 3/4.
Has anyone another suggestion about how to solve this PS question? Thanks in advance.
If you're looking for an alternate approach, one option is to use the complement:
P(red or white) = 1 - P(NOT red or white)
= 1 - P(blue)
= 1 - 5/20
= 15/20
= 3/4
Answer: A