Question

The table below shows the number of marbles of different colors in a bag:

Marble Experiment

Color of
Marbles Number of
Marbles
Red
5
White
8
Black
2


Deja draws a marble from the bag randomly without looking. She then draws another marble from the bag without replacing the first one. Which expression shows the probability of drawing red marbles in both the trials?
5 over 15 multiplied by 4 over 14
5 over 15 multiplied by 4 over 15
5 over 15 added to 4 over 14
5 over 15 added to 4 over 15

Answer 1

`\huge\boxed{\sf (5)/(15) + (4)/(14) }`

Explanation:

Formula for probability:

• 
  `\boxed{\displaystyle Probability = (number\ of\ possible\ outcomes)/(total\ number\ of \ outcomes) }`

Solution:

Total number of marbles = 5 + 8 + 2 = 15

Number of red marbles = 5

Probability to draw a red marble at the first trial = 5/15

Number of marbles left = 15 - 1 = 14

Number of Red marbles left = 5 - 1 = 4

Probability to draw a red marble at the second trial = 4/14

Total probability:

`\displaystyle =Probability \ of \ drawing \ a \ red \ marble \ at \ the \ (second \ attempt +first \ attempt)\\\\= (5)/(15) + (4)/(14) \\\\\rule[225]{225}{2}`