1. If one student were to be randomly selected from the 35 students in Mrs. Cornwall's class, the probability is 0.40 that a female student would be selected. How many female students are there in Mrs. Cornwall's class?
Answer: B
There are 14 female students in Mrs. Cornwall's class.
To determine the number of female students, we can use the probability given. Since the probability of selecting a female student is 0.40, we multiply this probability by the total number of students: 0.40 × 35 = 14.
A) 12
Choosing 12 female students would imply a probability of 12/35, which calculates to approximately 0.34. This does not match the given probability of 0.40, making this option incorrect.
B) 14
This option correctly represents the number of female students, as 0.40 multiplied by the total number of students (35) equals 14. Thus, this option aligns perfectly with the provided information.
C) 18
If there were 18 female students, the probability would be 18/35, which is approximately 0.51. This is inconsistent with the provided probability of 0.40, rendering this choice incorrect.
D) 21
Selecting 21 female students results in a probability of 21/35, or 0.60. This is significantly higher than the stated probability of 0.40, which confirms this option is also incorrect.
Conclusion
The correct answer is 14 female students, as this accurately reflects the probability of 0.40 when calculated against the total number of students in the class. All other options fail to meet the probability criteria established in the question, confirming their incorrectness.