# Help Needed for Probability Problem - 2nd Year Economics Student

• tunganhtr
In summary, the conversation is about a student in Economics who is having difficulties with probability. They present a problem where 50% of a sample of 18 students are expected to go up to the level of master, and the probability of at least 10 students going up is asked. They also inquire about the appropriate law of probability to use in this exercise. The expert points out that the previous answer given is incorrect and explains why it is called a "binomial" distribution.
tunganhtr
Hi, I am a 2nd year student in Economics. I have some difficulties with probability. Here is a problem that I cannot solve and I need some help.

It is supposed that only 50% of the students of a sample will go up to the level master. One chooses by chance 18 students.
Which is the probability so that at least 10 go up to the level master.

I want just to know in this exercise, which is the law of probability that one must apply.
Thank you for your assistance, and I'm so sorry for my bad English.

$$\Large \sum_{x=10}^{18}(.5)^x(.5)^{18-x}$$

Thanks you very much for the answer. It helps me a lot !
:)

tunganhtr, I feel I really should point out to you that marcmtlca's answer is INCORRECT. It doesn't help you as much as you think.

(In fact,
$$\Large \sum_{x=10}^{18}(.5)^x(.5)^{18-x}$$
$$= \Large \sum_{x= 10}^{18}(.5)^{18}$$
$$= 9(.5)^{18}= 0.00004196$$
which is much too small.)

Do you remember why this is called a "binomial" distribution?

## 1. What is probability?

Probability is a measure of the likelihood of an event occurring. It is expressed as a number between 0 and 1, where 0 represents impossibility and 1 represents certainty. It is used in many fields, including economics, to make predictions and decisions.

## 2. What types of probability problems might an economics student encounter?

An economics student might encounter probability problems related to predicting market trends, analyzing risk and uncertainty in decision making, or estimating the likelihood of different economic outcomes.

## 3. How can I improve my understanding of probability?

To improve your understanding of probability, it is important to practice solving various types of problems and familiarize yourself with the basic principles and formulas. You can also seek help from a tutor or attend study groups to discuss and work through problems with others.

## 4. Are there any common mistakes to watch out for when solving probability problems?

Yes, some common mistakes when solving probability problems include confusing the probability of an event with its odds, forgetting to account for all possible outcomes, and using incorrect formulas. It is important to carefully read and understand the problem and double-check your work to avoid making these mistakes.

## 5. Can probability be applied to real-world economic situations?

Yes, probability is widely used in economics to analyze and make predictions about various economic situations. It is used to assess risk and uncertainty in decision making, estimate the likelihood of future events, and evaluate the potential outcomes of different economic policies.

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