# Question 19d49

Apr 10, 2017

The probability of drawing two marbles is the product of drawing the each of the blue marbles.

The product of drawing the first marble is 4/16 or 1/4

The product of drawing the second marble is 3/15 = 1/5

The overall probability is

$\frac{1}{4} \times \frac{1}{5} = \frac{1}{20}$

Apr 10, 2017

Probability of drawing two blue marbles $= \frac{1}{20}$

#### Explanation:

Red Marbles $= 7$
Blue Marbles $= 4$
Green Marbles $= 5$

Total Marbles $= 7 + 4 + 5 = 16$

The probability value to be calculated as follows:

Probability of drawing two blue marbles = Number of ways two blue marbles can be taken from 4 blue marbles [number of favourable events] / Number of ways two marbles can be taken from the 16 marbles [Total Number of events]

Number of ways two blue marbles can be taken from 4 blue marbles [number of favourable events] $= n C r = 4 C 2 = 6$

Number of ways two marbles can be taken from the 16 marbles [Total Number of events] =nCr= 16C2=120

Probability of drawing two blue marbles $= \frac{6}{120} = \frac{1}{20}$