The gratuity on a restaurant bill was $18. If a 20% tip was left, what was the original amount of the bill? To solve, use what e
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Answer:
Step-by-step explanation:
Hello!
Since the data on the text is missing, I've found a similar exercise with the same questions so I'm going to use the data of that one to explain how to calculate the probabilities.
We have a sample of 323000 high school students
154000 are girls, of those 47700 dropped out
16900 are boys, of those 10300 dropped out
a) To calculate this probability you have to divide the total number of girls by the total number of students:
P(G)= 154000/323000= 0.476 ≅ 0.48
b) In this item you have to calculate the probability of dropouts, the total of students that dropped out are the girls + boys that dropped out:
Dropouts: 47700+10300= 58000
Now you divide it by the total of students to reach the probability:
P(D)= 58000/323000= 0.179≅ 0.18
c) Now you have to calculate the probability of the intersection between the events "female" and "dropped out", symbolically:
P(G∩D)= P(G)*P(D)= 0.48*0.18= 0.0864
d) The probability of the student dropping out given that it is female is a conditional probability and you can calculate using the following formula:
P(D/G)=<u> P(G∩D) </u>=<u> 0.0864 </u>= 0.18
P(G) 0.48
e) Now you have to calculate the probability of the student being a femal, given that she dropped out of school, symbolically:
P(G/D)=<u> P(G∩D) </u>=<u> 0.0864 </u>= 0.48
P(D) 0.88
Note:
As you can see in d) P(D/G)=P(D)=0.18 and in e) P(G/D)=P(G)=0.48, this means that both events "the student is a girl" and "the student dropped out" are independent.
Remember two events are not independent when the occurrence of one modifies the probability of occurrence of the other.
I hope it helps!
