00:01
The most efficient way to solve this problem is to organize the given information into a chart.
00:06
So we have information about chemistry students.
00:11
Some got an a plus, others did not.
00:16
We have information about biology students.
00:22
Once again, some got an a plus.
00:25
Some did not.
00:29
There was a total of 1 ,150 students.
00:37
Of those, 50, got an a plus.
00:40
Plus in chemistry, so that would mean there was 1 ,100 students that did not get an a plus in chemistry, and there were 375 students that got an a plus in biology, which would mean that there are 775 students that did not get the a plus in biology.
01:00
There were 45 students that received an a plus in both chemistry and biology.
01:07
So these two values should add up to 50, meaning that there were five students that got an a plus in chemistry, but not in biology.
01:18
These two locations should add up to 375.
01:25
So that means there are 330 students that got an a plus in biology, but not in chemistry.
01:32
And these two locations should add up to 775, meaning there were 770 students that did not get an a -plus in biology, nor did they get an a -plus in chemistry.
01:48
So therefore, we are now ready to answer your five questions.
01:54
So for part a, we are trying to determine the probability that a randomly selected student got an a -plus in biology, but not in chemistry.
02:17
So in order to do this, we have to think in terms of favorable over possible.
02:22
There were 45, sorry, 330 students that got the a plus in biology but not in chemistry out of a possible 1 ,150 students.
02:41
And we can write that as an equivalent fraction of 33 out of 115 or as a decimal of 0 .286 -956 -9 -6 -5 -6 -5 -2 -1 -7.
02:58
Now, this problem did not specify how to record your answer, so you may record it as a simplified fraction or a decimal.
03:08
So you're going to want to discuss that with your professor or teacher as to how you should record your answer.
03:14
And if he or she wants it as a decimal, how many decimal places should you round your result to? in part b, we want to determine the probability that a randomly selected student got the a plus in chemistry, but not in biology.
03:39
Once again, we're going to talk in terms of favorable over possible.
03:44
So there were five students that got the a plus in chemistry, but not in bio, out of a possible 1 ,100.
03:53
Students.
03:55
As a simplified fraction, that is the same as 1 out of 230, and as a decimal, that would be 0 .004, 347, 8261.
04:11
For part c, we want to determine the probability that a randomly selected student did not get the a -plus in biology or did not...