OST - Chapter 0 - Statistics and Probability

Greg buys a single coffee every weekday. He determines that the probability that he will buy a coffee on a random day in a 28-day period is 20/28. Greg also looks at weather records for the 28 days and sees that the temperature was above 240 C on 7 of the 28 days. Greg determines that the probability that the temperature will be above 24C and that he will buy a coffee is 5/28. Select a phrase and a word to complete the sentence identifying the effect of the average daily temperature when it was above 24C and Greg purchasing a coffee on a random day in the 28-day period. If the average daily temperature on a day is 24C or higher it is

• more likely that Greg will buy a cofee
• less likely that Greg will buy a coffee
• equally likely that Greg will buy a coffee

Greg buys a single coffee every weekday. He determines that the probability that he will buy a coffee on a random day in a 28-day period is 20/28. Greg also looks at weather records for the 28 days and sees that the temperature was above 240 C on 7 of the 28 days. Greg determines that the probability that the temperature will be above 24C and that he will buy a coffee is 5/28. Select a phrase and a word to complete the sentence identifying the effect of the average daily temperature when it was above 24C and Greg purchasing a coffee on a random day in the 28-day period. The two events are of Greg buying a coffee and the daily temperature are what type of events?

• independent
• dependent

Herman randomly selects a book from his library. He calculates the probabilities given. · P(hardcover or fiction) = 0.8 · P(hardcover and fiction) = 0.2 · P(hardcover) = 0.6 What is the probability that Herman selects a fiction book? (type answer as a decimal)

Probabilities for two events, event A and event B, are given. P( A and B ) = 0.14 P( B ) = 0.4 What is the probability of A given B ?

Maurice has a bag containing 40 small wooden blocks. · There are 20 cubes, of which 5 are blue. · There are 20 spheres, of which 6 are blue. Maurice randomly selects a cube from the bag. What is the probability that the cube he selects is blue? (enter answer as a decimal to 2 places)

A soccer coach determines that there is a 50% chance that a star player, Ralph, will play in a tournament. · The probability that another star player, Dan, will play is 0.48. · The probability that Ralph and Dan will play in the tournament is 0.25. Select phrases to complete the statement. To find the probability that either Ralph or Dan will play in the tournament,

• first add 0.50 and 0.48 then subtract 0.25 from the sum
• first add 0.50 and 0.25 then subtract 0.25 from the sum
• first add 0.50 and 0.48 then multiply the sum by 0.48
• first add 0.50 and 0.25 then multiply the sum by 0.48

Bryan records the number of hours he sleeps each night for several days and whether it is raining in the morning when he wakes up. Bryan concludes that these two events are independent: · Bryan sleeps 8 or more hours. · It is raining in the morning. Based on Bryans conclusions, which statement must be true?

• Bryan never sleeps 8 or more hours on days that it is not raining in the morning.
• The probability that Bryan sleeps 8 or more hours is the same whether or not it is raining in the morning.
• The probability that Bryan sleeps 8 or more hours is influenced by whether or not it is raining in the morning.
• The probability that Bryan sleeps 8 or more hours is the same as the probability that it is raining in the morning.

A total of 50 students play either soccer or lacrosse. · 20 girls play lacrosse. · 20 boys play either soccer or lacrosse. · 20 students play soccer. What is the probability that a student plays soccer or is a girl? (enter answer as a decimal)

Josh has a bag containing pieces of candy. The bag contains 10 red circular pieces, 10 red square pieces, 10 blue triangle pieces, and 10 blue star-shaped pieces. He draws a red piece of candy from the bag. What is the complement of this event?

• He draws a blue piece
• He draws a square piece
• He draws a circular piece
• He draws a star-shaped piece.

David has a stack of 30 cards, which are numbered 1 through 30. What is the exact probability of randomly selecting a card from the stack with a number that is even or is less than 10? (enter answer as a fraction)