Probability Concepts Quiz

Probability of Carrying No Cash

• Out of 3000 adults surveyed, 510 do not carry cash.
• The probability of a randomly selected adult carrying no cash is 510/3000, which simplifies to 17/100 or 0.17.

Birthday Probabilities

• Excluding leap years, there are 365 days in a year.
• The probability of a person having a birthday on the 1st of a month is 12/365.
• The probability of a person having a birthday on the 31st of a month is 7/365, as only seven months have 31 days.

Probability of Volunteering

• 341 out of 1100 surveyed female adults volunteered at least once in the past year.
• The probability of a randomly selected adult female volunteering at least once in the past year is 341/1100.

Odds Against Correctly Guessing

• A multiple-choice question has 5 possible answers.
• There is 1 correct answer and 4 incorrect answers.
• The odds against guessing correctly are 4:1, meaning there are 4 chances of being wrong for every 1 chance of being right.

Gender Sample Space and Probability

• A couple has 4 children, with each child having the possibility of being a boy (B) or a girl (G).
• The sample space for the genders of four births is represented by all possible combinations of B and G.
• This can be visualized using a tree diagram, leading to 16 possible outcomes:
  • BBBB, BBBG, BBGB, BBGG, BGBB, BGBG, BGGB, BGGG, GBBB, GBBG, GBGB, GBGG, GGBB, GGBG, GGGB, GGGG.
• The probability of having 3 girls and 1 boy (in any order) is 4/16 or 1/4, as there are 4 outcomes with 3 girls and 1 boy.