How many probability questions on gre

Before being able to solve a probability question, you must first be able to successfully identify one on the test. Common ones include:. One possible mistake you might make is confusing a proportion question for a probability question.

Proportion questions are arithmetic-based and concentrate heavily on ratios and percentages — not probability. But these two types of questions can take similar shapes on the GRE. For example:. After all, both are word-based questions containing fractions. Additionally, the first question offers decimals for answer choices which could signify probability , and the second question offers fractions for answer choices which could also signify probability.

There is no mention of probability or any key probability-related terms or phrases. Another strategy you can use is to determine a direction. Others, however, might ask you to work backward, starting with a probability and expecting you to instead solve for a specific number, such as the total number of people in a group or a certain number of items in a sample space.

To determine which direction to take in a probability problem, look at both the description and answer choices. If you are given a total number of items in a sample space from which something has been randomly selected, you will likely solve for the probability of choosing something.

Quantity A is not a probability but rather a number of specific people in a group. The problem states there are 25 people in a group. If the probability of a male being selected is 0. Remember, decimals are essentially the same as fractions. According to our calculations, there are 11 total males in this particular group of 25 people. The probability that a male chosen was born before is 0. Mimic the procedure above to calculate how many males in the group were born before We now know 7 of the 11 males in the group were born before But the question is asking us for the number of males born in or after We can use subtraction to get the answer:.

Because 4 is equal to Quantity B, the correct answer is C: The two quantities are equal. For the most part, you should be able to solve GRE probability questions using a combination of algebra and arithmetic. But some questions might be purposely vague or complicated. You most likely will not see such a question. Even if you do, getting the hang of these questions—indeed most probability questions on the test—just takes a little practice.

What scares you the most about probability? Anyway, let us know below. Some of his students have even gone on to get near-perfect scores. Probability is a way to describe uncertainty and the possible outcomes of an experiment using numbers. Simple probability determines the likelihood that an event will happen. Let us look at an example to understand simple probability better. When we perform an experiment, then the set of all the possible outcomes is called the sample space S.

When we roll a die, the possible outcomes are 1, 2, 3, 4, 5, and 6. Here, in our example of rolling a die the sample space is-. Any subset of the sample space is called an event. Now, the probability of rolling an even number is the number of outcomes that constitute the event divided by the total number of possible outcomes.

So, the probability of an event is determined using the following formula-. Therefore, the probability of getting an even number when we roll a die is-.

Thus, the probability of getting an even number while rolling a die is half. Or in other words, the probability of getting an even number when we roll a die is fifty percent. Apart from simple probability, the GRE probability section also tests your knowledge of permutation and combinations.

In very simple words, permutation refers to sequences and combination refers to groups. In a sequence order is important. Therefore, permutations are sequences where order is important, whereas in case of combinations, the order is not important.

Let us understand both these concepts with the help of an example. In how many different ways can five people sit in a row? In this question, we have to arrange five people in a sequence. One thing that has remained constant in all these years has been the number of probability questions that most people get on their GRE test. Probability questions vary from removing socks from a drawer to tossing coins and dices. Over years, I came across several students who mentioned GRE combining probability with geometry or with number properties.

For instance, the probability that a random point will fall within a shaded region of a circle or a triangle. Just practice a few questions and you should do well. Here is a practice question that would get you started and allay your probability woes. For the entire range of GRE probability questions, you can check this post. Q A certain jar contains 60 jelly beans—22 white, 18 green, 11 yellow, 5 red, and 4 purple.