Unizor - Probability - Definition - Problems 2
Channel: Zor Shekhtman on UNIZOR Education
Date: 07/08/2014

There are 8 people in the room:
A - male, 19 years of old;
B - male, 18 years of old;
C - female, 18 years of old;
D - male, 20 years of old;
E - male, 24 years of old;
F - female, 28 years of old;
G - male, 33 years of old;
H - female, 16 years of old.

(a) Describe in words an event X consisting of the following elementary events C, F an H.
Answer:
Randomly picked person is a female.

(b) Let event X be {A,B,C,D,H}. Describe this event in words.
Answer:
Randomly picked person is 20 years old and younger.

(c) Let event X={C}. Describe this event in words.
Answer:
Randomly picked person is a female of 18 years old.

(d) Let event X={E,F,G} and event Y={A,B,D,E,G}. Describe the event X AND Y in words.
Answer:
Randomly picked person is a male of 24 years old and older.

(e) Let event X={E,F,G} and event Y={A,B,D,E,G}. Describe the event X AND Y in words using negation NOT in relation to the person's age.
Answer:
Randomly picked person is a male of NOT younger than 24 years old.

(f) Let event X={E,F,G} and event Y={A,B,D,E,G}. Describe the event X AND NOT Y in words.
Answer:
Randomly picked person is of 24 years old and older and not a male (in other words, female of at least 24 years old).

(g) Let event X={E,F,G} and event Y={A,B,D,E,G}. Describe the event NOT X AND Y in words.
Answer:
Randomly picked person is younger than 24 years old and is a male.

(h) Let event X={C,F,H} and event Y={A,B,D,E,G}. Describe the event X OR Y in words.
Answer:
Randomly picked person is either male or female, that is randomly picked person is any person. This event encompasses an entire sample space.

(i) Let event X={A,B,D,E,G} and event Y={C,F}. Describe the event X OR Y in words.
Answer:
Randomly picked person is either a male or a female older than 16 years old.