Simple
If there are seven red marbles and five blue marbles in a bag, what is the probability to pull out a blue marble?
5/12
A fair die is thrown 3 times . The chance that sum of three numbers appearing on the die is less than 11 , is equal to -
1/2
Lisa has to choose one of each: a shirt and a pair of pants to pick out tomorrow’s complete attire. She has options from four shirts and three pairs of pants. How many different combinations can she make?
4*3=12
Probability
The chances of something happening.
A bag contains 3 red marbles and 7 blue marbles. You remove a random marble from the bag, record the color, and put it back into the bag. Then you remove another marble from the bag and record its color. Solve this.
P(R, B)=
P(R, R)=
P(B,B)=
P(R,B)= 3/10 x 7/10 = 21/100
P(R,R)= 3/10 x 3/10 = 9/100
P(B,B)=7/10 x 7/10 = 49/100
A bag contains 3 red marbles and 7 blue marbles. You remove a random marble from the bag, record the color and you DON'T put it back into the bag. Then you remove another marble from the bag and record its color. Solve this.
P(R,B)=
P(B,R)=
P(B,B)=
P(R,R)=
P(R,B)= 3/10 x 7/9 = 7/80
P(B,R)= 7/10 x 3/9 = 7/30
P(B,B)= 7/10 x 6/9 = 7/15
P(R,R)= 3/10 x 2/9 = 1/15
There are 15 flavors of ice-cream, and 7 different cones. How many different single scoop ice creams can you order?
7x15= 105
Outcome
The possible result of a probability experiment
Find the probability of getting an odd number less than 6 in a single throw of a die.
Possible outcomes = {1,2,3,4,5,6}
Favorable outcomes = Getting an odd number less than 6= {2,4}
P(Getting an odd number less than 6) = 2/6 = 1/3
You flip a coin and roll a die at the same time. What is the probability you will flip a tail and roll a four?
P(tossing a head)= 1/2
P(rolling a 4)= 1/6
P(tossing heads and rolling a four)= 1/2 x 1/6 = 1/12
There are 3 blue chips and 7 red chips in a bag. One chip is drawn from the bag and is not replaced. A second chip is then drawn. What is the probability that the two selected chips are the same colors?
P(B B) + P (R R)
= 3/10*2/9 + 7/10*6/9
= 6/90 + 42/90 = 48/90
Independent Events
2 or more events whose outcomes do not affect each other
What is the probability to get prime numbers from a roll of a dice, and then getting heads right away from a throw of the coin?
1/2 x 1/2 = 1/4
A bag contains 3 black balls, 2 green balls. Jake picks a ball, then another ball without putting the first one back in the bag, what is the probability of picking two green balls
P(G,G) = 2/5 x 1/4 = 1/10
In a group of nine students, four are girls and five are boys. If the chaperone randomly selects two students, what is the probability that two girls are chosen?
4/9 * 3/8 = 1/6
Dependent Events
I2 or more events whose outcomes affect each other.