Probability that the selected student will be in an odd-numbered grade

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Homework Help Overview

The problem involves calculating probabilities related to a school with students in grades 1 through 6, where the distribution of students varies by grade. Specifically, it asks for the probability of selecting a student from grade 3 and the probability of selecting a student from an odd-numbered grade.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to define the sizes of each grade using a variable, expressing the total population in terms of this variable. Some participants question how to derive the sample space and the probabilities from the given information.

Discussion Status

Some participants have provided insights into calculating the total number of students based on the variable defined by the original poster. There is an ongoing exploration of how to apply this to find the required probabilities, with some responses indicating a misunderstanding of the total population size.

Contextual Notes

The original poster expresses uncertainty about how to proceed with the problem, indicating a need for clarification on the setup and calculations involved in determining probabilities.

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Homework Statement



A school contains students in grades 1,2,3,4,5 and 6. Grades 2,3,4,5 and 6 all contain the same number of students, but there are twice this number in grade 1.

a)If a student is selected at random from a list of all the students in the school, what is the probability that he will be in grade 3?
b)What is the probability that the selected student will be in an odd-numbered grade?

Homework Equations





The Attempt at a Solution



Let n=the size of grade(s) 2,(3,4,5,6) then 2n=the size of grade 1.
So the size of the sample space I don't know how to find.
I really need help on this. I am not sure what to do from here at all. Thanks.
 
Last edited:
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This is really just testing how you work with variables. Since you have n = the size of grades 2,3,4,5,6, and 2n = size of grade 1, the school's population must be 2n + 5*n, where the 2n represents the size of grade 1, and the 5*n represents the size of grades greater than 1 (since there are 5 of them). Therefore, the population is 7n. Given this fact, how would you be able to find the probabilities of a) and b)?
 


ok, I see the response above.
 
Last edited:


so the event (student chosen is in grade 3) has size=7
so the probability is =1/7
 
Last edited:

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