All SAT Math Resources
Example Questions
Example Question #51 : Probability
In a hotel with 120 rooms, 30 of them have red carpet. A hotel manager has lost his keys somewhere in the hotel. If there is an equal chance of the keys being in any room, what is the probability that they are in a room with red carpet?
Probability = desired outcomes divided by total possible outcomes
Example Question #61 : How To Find The Probability Of An Outcome
A bag contains the following numbers of apples: 12 red delicious, 10 granny smith, and 7 fuji apples. If an apple is selected at random, what is the probability it is either a granny smith or a fuji apple?
Probability = desired outcomes divided by total possible outcomes. Desired outcome can be either fuji or granny smith.
Desired outcomes
Total outcomes
Example Question #58 : Probability
From a class consisting of 15 girls and 12 boys, two students are chosen at random to be class representatives. What is the probability that neither of the two students chosen is a boy?
To satisfy the question, BOTH students chosen must be girls.
First selection: 15 girls of 27 total students:
Second selection: 14 girls out of 26 total students:
Example Question #59 : Probability
If 2 six-sided dice, each with sides numbered 1-6, are rolled, what is the probability that the sum of the numbers on the face-up sides is equal to 7?
Probability = desired outcomes divided by total possible outcomes.
Desired outcomes = 6 (1,6; 2,5; 3,4; 4,3; 5,2; 6;1)
Total outcomes - 36
Example Question #61 : How To Find The Probability Of An Outcome
If an 8-sided die is rolled 3 times, what is the probability that the same number will be rolled each time?
Another way to look a it is there are 512 total possible outcomes and 8 desired outcomes.
Example Question #61 : How To Find The Probability Of An Outcome
If a two-sided coin is flipped four times, what is the probability of never getting a head?
The probability of never getting a head is the same as always getting tails. This is .
Example Question #61 : How To Find The Probability Of An Outcome
If a six-sided die is thrown four times, what is the probability of getting a four everytime?
The probability is .
Example Question #222 : Data Analysis
If there are 9 marbles in a bag, three white, three blue, and three red, what is the probability of selecting three red marbles at random?
The probability of selecting 3 red marbles is .
Example Question #61 : How To Find The Probability Of An Outcome
There is a box containing 2 red marbles, 7 blue marbles, and an unknown number of green marbles. If the probably of drawing a red marble is 10%, what is the probably that one draws a green marble?
Let be the total number of marbles in the box. Since there's a 10% chance of drawing a red marble, then implies there are 20 marbles total in the box. Thus, there are only 11 green marbles, resulting in the probability of drawing a green marble being
Example Question #222 : Data Analysis
A person rolls a fair 6-sided die twice. What is the probability that the sum of the two rolls is 3?
In order for the sum to be 3, the two rolls must be 1 and 2. However, it doesn't matter which one comes first. Therefore, there are 2 ways we can acquire the sum being 3. The total number of combination of two die is .
Thus, the probability of rolling a sum of 3 is .