Respuesta :
Answer:
For probabilities with replacement
[tex]P(2\ Red) = \frac{25}{64}[/tex]
[tex]P(2\ Black) = \frac{9}{64}[/tex]
[tex]P(1\ Red\ and\ 1\ Black) = \frac{15}{32}[/tex]
[tex]P(1st\ Red\ and\ 2nd\ Black) = \frac{15}{64}[/tex]
For probabilities without replacement
[tex]P(2\ Red) = \frac{5}{14}[/tex]
[tex]P(2\ Black) = \frac{3}{28}[/tex]
[tex]P(1\ Red\ and\ 1\ Black) = \frac{15}{28}[/tex]
[tex]P(1st\ Red\ and\ 2nd\ Black) = \frac{15}{56}[/tex]
Step-by-step explanation:
Given
[tex]Marbles = 8[/tex]
[tex]Red = 5[/tex]
[tex]Black = 3[/tex]
For probabilities with replacement
(a) P(2 Red)
This is calculated as:
[tex]P(2\ Red) = P(Red)\ and\ P(Red)[/tex]
[tex]P(2\ Red) = P(Red)\ *\ P(Red)[/tex]
So, we have:
[tex]P(2\ Red) = \frac{n(Red)}{Total} \ *\ \frac{n(Red)}{Total}\\[/tex]
[tex]P(2\ Red) = \frac{5}{8} * \frac{5}{8}[/tex]
[tex]P(2\ Red) = \frac{25}{64}[/tex]
(b) P(2 Black)
This is calculated as:
[tex]P(2\ Black) = P(Black)\ and\ P(Black)[/tex]
[tex]P(2\ Black) = P(Black)\ *\ P(Black)[/tex]
So, we have:
[tex]P(2\ Black) = \frac{n(Black)}{Total}\ *\ \frac{n(Black)}{Total}[/tex]
[tex]P(2\ Black) = \frac{3}{8}\ *\ \frac{3}{8}[/tex]
[tex]P(2\ Black) = \frac{9}{64}[/tex]
(c) P(1 Red and 1 Black)
This is calculated as:
[tex]P(1\ Red\ and\ 1\ Black) = [P(Red)\ and\ P(Black)]\ or\ [P(Black)\ and\ P(Red)][/tex]
[tex]P(1\ Red\ and\ 1\ Black) = [P(Red)\ *\ P(Black)]\ +\ [P(Black)\ *\ P(Red)][/tex]
[tex]P(1\ Red\ and\ 1\ Black) = 2[P(Red)\ *\ P(Black)][/tex]
So, we have:
[tex]P(1\ Red\ and\ 1\ Black) = 2*[\frac{5}{8} *\frac{3}{8}][/tex]
[tex]P(1\ Red\ and\ 1\ Black) = 2*\frac{15}{64}[/tex]
[tex]P(1\ Red\ and\ 1\ Black) = \frac{15}{32}[/tex]
(d) P(1st Red and 2nd Black)
This is calculated as:
[tex]P(1st\ Red\ and\ 2nd\ Black) = [P(Red)\ and\ P(Black)][/tex]
[tex]P(1st\ Red\ and\ 2nd\ Black) = P(Red)\ *\ P(Black)[/tex]
[tex]P(1st\ Red\ and\ 2nd\ Black) = \frac{n(Red)}{Total} *\ \frac{n(Black)}{Total}[/tex]
So, we have:
[tex]P(1st\ Red\ and\ 2nd\ Black) = \frac{5}{8} *\frac{3}{8}[/tex]
[tex]P(1st\ Red\ and\ 2nd\ Black) = \frac{15}{64}[/tex]
For probabilities without replacement
(a) P(2 Red)
This is calculated as:
[tex]P(2\ Red) = P(Red)\ and\ P(Red)[/tex]
[tex]P(2\ Red) = P(Red)\ *\ P(Red)[/tex]
So, we have:
[tex]P(2\ Red) = \frac{n(Red)}{Total} \ *\ \frac{n(Red)-1}{Total-1}[/tex]
We subtracted 1 because the number of red balls (and the total) decreased by 1 after the first red ball is picked.
[tex]P(2\ Red) = \frac{5}{8} * \frac{4}{7}[/tex]
[tex]P(2\ Red) = \frac{5}{2} * \frac{1}{7}[/tex]
[tex]P(2\ Red) = \frac{5}{14}[/tex]
(b) P(2 Black)
This is calculated as:
[tex]P(2\ Black) = P(Black)\ and\ P(Black)[/tex]
[tex]P(2\ Black) = P(Black)\ *\ P(Black)[/tex]
So, we have:
[tex]P(2\ Black) = \frac{n(Black)}{Total}\ *\ \frac{n(Black)-1}{Total-1}[/tex]
We subtracted 1 because the number of black balls (and the total) decreased by 1 after the first black ball is picked.
[tex]P(2\ Black) = \frac{3}{8}\ *\ \frac{2}{7}[/tex]
[tex]P(2\ Black) = \frac{3}{4}\ *\ \frac{1}{7}[/tex]
[tex]P(2\ Black) = \frac{3}{28}[/tex]
(c) P(1 Red and 1 Black)
This is calculated as:
[tex]P(1\ Red\ and\ 1\ Black) = [P(Red)\ and\ P(Black)]\ or\ [P(Black)\ and\ P(Red)][/tex]
[tex]P(1\ Red\ and\ 1\ Black) = [P(Red)\ *\ P(Black)]\ +\ [P(Black)\ *\ P(Red)][/tex]
[tex]P(1\ Red\ and\ 1\ Black) = [\frac{n(Red)}{Total}\ *\ \frac{n(Black)}{Total-1}]\ +\ [\frac{n(Black)}{Total}\ *\ \frac{n(Red)}{Total-1}][/tex]
So, we have:
[tex]P(1\ Red\ and\ 1\ Black) = [\frac{5}{8} *\frac{3}{7}] + [\frac{3}{8} *\frac{5}{7}][/tex]
[tex]P(1\ Red\ and\ 1\ Black) = [\frac{15}{56} ] + [\frac{15}{56}][/tex]
[tex]P(1\ Red\ and\ 1\ Black) = \frac{30}{56}[/tex]
[tex]P(1\ Red\ and\ 1\ Black) = \frac{15}{28}[/tex]
(d) P(1st Red and 2nd Black)
This is calculated as:
[tex]P(1st\ Red\ and\ 2nd\ Black) = [P(Red)\ and\ P(Black)][/tex]
[tex]P(1st\ Red\ and\ 2nd\ Black) = P(Red)\ *\ P(Black)[/tex]
[tex]P(1st\ Red\ and\ 2nd\ Black) = \frac{n(Red)}{Total} *\ \frac{n(Black)}{Total-1}[/tex]
So, we have:
[tex]P(1st\ Red\ and\ 2nd\ Black) = \frac{5}{8} *\frac{3}{7}[/tex]
[tex]P(1st\ Red\ and\ 2nd\ Black) = \frac{15}{56}[/tex]