Select the correct answer.

Bonnie has 4 sharpened and 8 unsharpened pencils in her pencil case. She randomly selects 2 of the pencils from the box without replacement. What is the probability that both pencils will be sharpened?

A. [tex]\frac{1}{12}[/tex]
B. [tex]\frac{1}{9}[/tex]
C. [tex]\frac{4}{33}[/tex]
D. [tex]\frac{1}{11}[/tex]



Answer :

To solve this problem, we need to calculate the probability of drawing 2 sharpened pencils in succession without replacement from a total of 12 pencils (consisting of 4 sharpened and 8 unsharpened pencils).

Let's break down the problem into two steps - one for each draw.

### Step 1: Probability of the First Draw

- Total pencils: 12 (4 sharpened + 8 unsharpened).
- Sharpened pencils: 4

The probability of drawing a sharpened pencil on the first draw is the ratio of the number of sharpened pencils to the total number of pencils:

[tex]\[ P(\text{First sharpened}) = \frac{\text{Number of sharpened pencils}}{\text{Total number of pencils}} = \frac{4}{12} = \frac{1}{3} \][/tex]

### Step 2: Probability of the Second Draw

After drawing one sharpened pencil, there are 11 pencils left in the box and 3 of them are sharpened.

- Total pencils left: 11
- Sharpened pencils left: 3

The probability of drawing another sharpened pencil on the second draw, given that the first pencil drawn was sharpened, is:

[tex]\[ P(\text{Second sharpened | First sharpened}) = \frac{\text{Number of remaining sharpened pencils}}{\text{Total remaining pencils}} = \frac{3}{11} \][/tex]

### Total Probability

Since these are two independent events that must both happen, we multiply the probabilities of both events:

[tex]\[ P(\text{Two sharpened pencils}) = P(\text{First sharpened}) \times P(\text{Second sharpened | First sharpened}) = \frac{1}{3} \times \frac{3}{11} \][/tex]

Simplifying this multiplication:

[tex]\[ P(\text{Two sharpened pencils}) = \frac{1 \times 3}{3 \times 11} = \frac{3}{33} = \frac{1}{11} \][/tex]

So, the correct probability that both pencils drawn will be sharpened is:

[tex]\[ \boxed{\frac{1}{11}} \][/tex]