There are 10 pens in a box. There are x red pens in the box. All the other pens are blue. Jack takes at random two pens from the

Question

3 years ago

5

box. Find an expression, in terms of x, for the probability that Jack takes one pen of each colour. Give your answer in its simplest form.

1 answer:

expeople1 [14] · Answer 1 · 2022-08-09T12:08:12+03:00

The probability that one of each color is selected is $\frac{10x - x^2}{45}$

<h3>Probabilities</h3>

The probability of an event is the chances of the said event

The given parameters are:

<h3>Calculating the required probability</h3>

The probability that one of each color is selected is calculated as follows:

$P = P(Blue) \times P(Red) + P(Red) \times P(Blue)$

So, we have:

$P = \frac{10 - x}{10} \times \frac{x}{9} + \frac{x}{10} \times \frac{10 - x}{9}$

This gives

$P = \frac{x(10 - x)}{90} +\frac{x(10 - x)}{90}$

Take LCM

$P = \frac{2x(10 - x)}{90}$

Simplify the above expression

$P = \frac{x(10 - x)}{45}$

Expand

$P = \frac{10x - x^2}{45}$

Hence, the probability that one of each color is selected is $P = \frac{10x - x^2}{45}$