All PSAT Math Resources
Example Questions
Example Question #62 : 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 #62 : Probability
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 #1511 : Psat Mathematics
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 #63 : How To Find The Probability Of An Outcome
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 .
Example Question #66 : How To Find The Probability Of An Outcome
A card is drawn randomly from a stardard 52-card deck. What is the probability of drawing a four of hearts?
The question is asking for the probability of drawing a 4 AND a Heart.
Prob(draw a 4) .
Prob(draw a Heart) .
Then the Prob(4 AND Heart) = Prob(4) * Prob(Heart)
You can also solve this question using logic instead of the rules of probability. We know there is only one four of hearts in a deck of cards, so the probability of drawing one must be .
Example Question #1512 : Psat Mathematics
How many different ways can 15 runners receive ribbons in a race if 1st, 2nd, 3rd, and 4th place ribbons are given?
Order matters, so a permutation of 15 things chosen 4 at a time, or , is the correct answer.
Example Question #63 : Probability
A bag of marbles consists of 13 green, 15 blue, 12 black and an unknown number of red marbles. If the chance of choosing a red marble is 1 in 3, how many marbles are there total?
Adding the green, blue, and black marbles together gives 40. Then if there is a chance that a red marble is drawn, there must be an additional 20 marbles.
Example Question #64 : Probability
Tiffany picks a peice of fruit from a bowl at random. The bowl contains 2 red delicious apples, 3 granny smith apples, 1 orange and 3 grapefruits. What is the probability that she chooses an apple?
The chance she picks an apple is the total number of apples over the total number of fruits in the bowl. Since there are 2 kinds of apples, we add 2 red delicious and 3 granny smiths to get 5 apples total. In addition there are 4 more peices of fruit, so the total number of fruits is 9.
Example Question #1511 : Psat Mathematics
In a bag, there are 6 black marbles and 8 yellow marbles. What is the possibility of choosing a yellow marble at random?
There is a total of 14 marbles, of which, 8 are yellow; therefore the probability of choosing a yellow marble is or
Example Question #1512 : Psat Mathematics
In a bag, there are 6 black and 8 yellow marbles. A yellow marble is chosen at random and is not replaced. What is the probability of choosing a second yellow marble?
Because a yellow marble was selected and not replaced, there is a total of 13 marbles in the bag and of which, 7 are yellow; therefore, the probability of selecting a yellow marble is