Question

(a) A box contains marbles which are marked with first ten natural numbers. Find the probability of getting a marble marked with a multiple of 2.

(b) A bag contains 3 red balls, 6 blue balls, 1 is black and 2 balls are green. If you want to pick out a red ball what is the probability that you will get a red ball? [3 MARKS]

Answer 1

Part a: 1.5 Marks
Part b: 1.5 Marks

(a) First ten natural numbers = 1,2,3,4,5,6,7,8,9,10.

$\Rightarrow$ Total number of natural numbers = 10

Multiple of 2 = 2,4,6,8,10.

$\Rightarrow$ Number of multiples of 2 are = 5

Probability of getting multiple of 2:
$=\frac{\text{Number of multiples of 2}}{\text{Total number of natural numbers}}$

$\Rightarrow \text{P(E)}=\frac{5}{10}=\frac{1}{2}$

(b) Total number of balls in the bag = 3 + 6 + 1 + 2 = 12

Probability of getting a red ball:
$=\frac{\text{Number of red balls}}{\text{Total number of balls}}$

$\Rightarrow P\left(E\right)=\frac{3}{12}=\frac{1}{4}$