Left hand! right hand
Female___!________
Male_____!_______
Total-18 ! 122
The incomplete table above summarizes the number of left-handed students and right-handed students by gender for the eighth grade students at Keisel Middle School. There are 5 times as many right-handed female students as there are left-handed female students, and there are 9 times as many right-handed male students as there are left-handed male students. if there is a total of 18 left-handed students and 122 right-handed students in the school, which of the following is closest to the probability that a right-handed student selected at random is female? (Note: Assume that none of the eighth-grade students are both right-handed and left-handed.)
A) 0.410
B) 0.357
C) 0.333
D) 0.250
jnkl
To solve this problem, we need to determine the number of right-handed female students and the total number of right-handed students, and then divide the former by the latter to find the probability.
Let's first determine the number of right-handed female students. We are given that there are 5 times as many right-handed female students as there are left-handed female students. Since there are 18 left-handed students in total, we can assume that there are 18/5 = 3.6 left-handed female students. However, since we cannot have a fraction of a student, we can assume there are 4 left-handed female students (round up to the nearest whole number). Therefore, there are 4 * 5 = 20 right-handed female students.
Now, let's determine the total number of right-handed students. We are given that there are 9 times as many right-handed male students as there are left-handed male students. Since there are 122 right-handed students in total, we can assume there are 122/9 = 13.56 left-handed male students. Again, since we cannot have a fraction of a student, we can assume there are 14 left-handed male students (round up to the nearest whole number). Therefore, there are 14 * 9 = 126 right-handed male students.
Finally, we can calculate the total number of right-handed students by adding the number of right-handed female students to the number of right-handed male students: 20 + 126 = 146.
To find the probability that a right-handed student selected at random is female, we divide the number of right-handed female students by the total number of right-handed students: 20 / 146 ≈ 0.137 (rounded to three decimal places).
The closest answer option to this result is:
A) 0.410
Therefore, the correct answer is A) 0.410.
RF = 5LF
RM = 9LM
LF+LM = 18
RF+RM = 122
RF=50
LF=10
RM=72
LM=8
So, fill in the table, and you should quickly find the answer.
Note: Also assume that none of the students is both male and female.