Probability - ISEE Middle Level Math

The probability of an event based on observation (empirical probability) can be calculated by dividing the number of times the event occurs by the number of trials total. Since there were trials and heads, there were tails.

The probability of tails is therefore given by the number of tails divided by the total number of trials. Both terms are divisible by , allowing us to simplify the fraction.

There are 13 yellow and red pebbles. There are 25 pebbles total. Therefor the probability of choosing a red or yellow pebble is .

The rolls that yield a product between and inclusive are:

Therefore there are rolls that fit our criteria out of a total of possible rolls, so the probability of this outcome is .

Find the color with the largest number of marbles in the bag.

Answer: There are more blue marbles in the bag, therefore it would be more likely to pick a blue marble.

There are four cards of each rank in a standard deck; since three ranks - jacks, queens, kings - are considered face cards, this makes twelve face cards out of the fifty-two. But two of those face cards - two red queens - have been removed, so now there are ten face cards out of fifty. This makes the probability of a randomly drawn card being a face card

.

Probability is determined by dividing the possible number of instances of a particular outcome by the total number of possible outcomes. Therefore, we need to find the probability of drawing red, blue, or white divided by the total number of outcomes.

Probability is determined by dividing the number of incidences of a specific outcome (in this case rolling greater than 4, or rolling a 5 or 6) by the total number of outcomes (there are 6 sides to the die).

Probability is determined by dividing the number of outcomes of a particular event by the total number of events. In a regular deck of playing cards, there are 52 cards and 13 diamonds.

The following rolls result in the difference of the dice being :

and the reverse of each of these.

These are rolls out of a possible , so the probability of this event is

There are seven days in a week.

The probability that a person you meet was born on any particular day is .

The question asks for the probability that the person you meet was born on a weekend (Saturday or Sunday). Therefore, we must add the probability of being born on either day:

One-ninth of the 36 possible rolls is 4, so we are looking for an outcome that can happen four ways.

There are 6 ways that both dice can show the same number - double 1, double 2, and so forth.

There are 3 ways to roll a sum of 10: (4,6), (5,5), and (6,4).

There are 6 ways to roll a sum divisible by 6: (1,5), (2,4), (3,3), (4,2), and (5,1) all yield 6, and (6,6) yields 12.

There are 4 ways to roll a sum of 5: (1,4), (2,3), (3,2), and (4,1).

There are 3 ways to roll a sum of 4: (1,3), (2,2), (3,1).

The correct choice is the event that the sum of the dice is 5.

A standard deck contains cards including jacks, of which are red. Therefore, the probability is:

The probability (p) is equal to the number of a specific event (purple marbles) divided by the total number of events. The probability of NOT p (called q) is equal to In this example:

To find probability, you have to consider part over whole. The total number of marbles is 12. Then, identify how many red marbles there are (3). From there, you can make a fraction , which can be simplified to .

The pizza that Billy's mom baked was composed of these types of slices:

Half the slices have pepperoni only. Two of the slices have both pepperoni and onoins. One slice has onions only. One slice has only cheese.

Therefore,

slices had pepperoni because

slices had pepperoni and onions

slice had onion only

slice had only cheese.

Billy could eat either the onion only slice, or the cheese only slice. This means that out of pieces of pizza, he could eat .

Given that is the percent equivalent of , that is the correct answer.

If 10 percent of puppies are born with spots, and of those, 50 percent have black spots, then the total percent of puppies who have spots AND the color of the spots is black can be found by multiplying the two percentages by one another:

0.05 is the equivalent of 5 percent, the correct answer.

Given that of the class is girls, and there are students, we must first determine how many girls are in the class.

Because is double the value of , is double the value of . should be half of .

If of the girls wear skirts, then we can subtract to find the number of girls not wearing skirts.

There are 10 total participants in the raffle.

288, 289, 290, 291, 292, 292, 294, 295, 296, 297

Only 2 participants have tickets with numbers that beging in 2 and 8.; therefore, Jenny has a 50 percent chance of holding the winning raffle ticket.

The winner is either 288 or 289, leaving Jenny a 50 percent chance.

Given that in Gina’s bag of 12 marbles, half of them are black and half are white, this means that there are 6 black marbles and 6 white marbles. However, because she already picked out 2 white marbles, this means that there are now only 4 out of 10 white marbles left. 4 out of 10 converts to 40 percent, which is therefore the correct answer.