Probability, SM-Bank 034

Francine has a bag of marbles.

The number of marbles of each colour is recorded in the table below.

\begin{array} {|l|c|}
\hline
\rule{0pt}{2.5ex} \textbf{Colour} \rule[-1ex]{0pt}{0pt} & \textbf{Number of marbles} \\
\hline
\rule{0pt}{2.5ex} \textbf{green} \rule[-1ex]{0pt}{0pt} & 14 \\
\hline
\rule{0pt}{2.5ex} \textbf{blue} \rule[-1ex]{0pt}{0pt} & 7 \\
\hline
\rule{0pt}{2.5ex} \textbf{white} \rule[-1ex]{0pt}{0pt} & 3 \\
\hline
\rule{0pt}{2.5ex} \textbf{red} \rule[-1ex]{0pt}{0pt} & 4 \\
\hline
\end{array}

Francine randomly takes 1 marble out of her bag without looking.

What is the chance it is green? (1 mark)
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What is the chance it is red or white? (1 mark)
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What is the chance it is yellow? (1 mark)
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Show Answers Only

a. \(\dfrac{1}{2}\)

b. \(\dfrac{1}{4}\)

c. \(0\)

Show Worked Solution

a. \(P\text{(green)}\)	\(=\dfrac{\text{Number of green}}{\text{Total number}}\)
	\(=\dfrac{14}{28}\)
	\(=\dfrac{1}{2}\)

b. \(P\text{(red or white)}\)	\(=\dfrac{\text{Number of red and white}}{\text{Total number}}\)
	\(=\dfrac{4+3}{28}\)
	\(=\dfrac{1}{4}\)

c. \(\text{There are no yellow marbles}\)

\(\therefore\ P\text{(yellow)}=0\)