Question

Need help pleaseI was bad at math in school so lwant to learn

Answer 1

The probability of an event is expressed as

$Pr(\text{event) =}\frac{Total\text{ number of favourable/desired outcome}}{Tota\text{l number of possible outcome}}$

Given:

$\begin{gathered} \text{Red}\Rightarrow2 \\ \text{Green}\Rightarrow3 \\ \text{Blue}\Rightarrow2 \\ \Rightarrow Total\text{ number of balls = 2+3+2=7 balls} \end{gathered}$

The probability of drwing two blue balls one after the other is expressed as

$Pr(\text{blue)}\times Pr(blue)$

For the first draw:

$\begin{gathered} Pr(\text{blue) = }\frac{number\text{ of blue balls}}{total\text{ number of balls}} \\ =\frac{2}{7} \end{gathered}$

For the second draw, we have only 1 blue ball left out of a total of 6 balls (since a blue ball with drawn earlier).

Thus,

$\begin{gathered} Pr(\text{blue)}=\frac{number\text{ of blue balls left}}{total\text{ number of balls left}} \\ =\frac{1}{6} \end{gathered}$

The probability of drawing two blue balls one after the other is evaluted as

$\begin{gathered} \frac{1}{6}\times\frac{2}{7} \\ =\frac{1}{21} \end{gathered}$

The probablity that none of the balls drawn is blue is evaluted as

$\begin{gathered} 1-\frac{1}{21} \\ =\frac{20}{21} \end{gathered}$

Hence, the probablity that none of the balls drawn is blue is evaluted as

$\frac{20}{21}$