# Probability part 2

• Dec 16th 2009, 01:39 PM
JJC85
Probability part 2
========Men Women Total
Domestic = 52 = 290 = 342
Acquaintance = 445 = 321 = 766
Stranger = 581 = 167 = 748
Mugging = 247 = 145 = 392
Total = 1325 = 923 = 2248

Probability

i. Domestic = 342/2242 = 0.15 or 15% (is this correct?)

ii. Stranger and victim was a woman = 167/923 = 0.18 or 18% (is this correct?)

iii. Mugging given that the victim was a man = 247/1325 = 0.19 or 19% (is this correct?)

iv. Against a woman or carried out by a stranger

v. Against a man given that it was domestic

vi. Are the events domestic and man independent?

Thanks
• Dec 17th 2009, 03:48 PM
qmech
i, ii, and iii are correct
• Dec 17th 2009, 06:09 PM
Soroban
Hello, JJC85!

Quote:

$\begin{array}{c||c|c||c|}
& \text{Men} & \text{Women} & \text{Total} \\ \hline\hline
\text{Domestic} & 52 & 290 & 342 \\
\text{Acquaintance} & 445 & 321 & 766 \\
\text{Stranger} & 581 & 167 & 748 \\
\text{Mugging} & 247 & 145 & 392 \\ \hline
\text{Total} & 1325 & 923 & 2248
\end{array}$

Probability

i. Domestic = $\frac{342}{2248} \:\approx\:15\%\quad\text{is this correct?}$ . Yes

ii. Stranger and victim was a woman = $\frac{167}{923} \:\approx\:18\%\quad\text{(is this correct?)}$ . No

$P(\text{stranger }\wedge\text{ woman}) \:=\:\frac{167}{2248} \:\approx\:7\%$

Quote:

iii. Mugging, given that the victim was a man = $\frac{247}{1325} \:\approx\:19\%\;\;\text{(is this correct?)}$ .Yes

iv. Against a woman or carried out by a stranger

"Against a woman or carried out by a stranger": . $923 + 581 \,=\,1504$

$\text{Prob. } \:=\:\frac{1504}{2248} \:\approx\:67\%$

Quote:

v. Against a man, given that it was domestic

$\text{Prob.} \:=\:\frac{52}{342} \:\approx\:15\%$

Quote:

vi. Are the events Domestic and Man independent? . No