Answer #3: Letters a,b,c,d Answer #4: Letters a,b,c 3. You conducted a survey to
ID: 3062084 • Letter: A
Question
Answer #3: Letters a,b,c,d Answer #4: Letters a,b,c 3. You conducted a survey to learn more about the student body of CCD. You asked 500 students whether they have a family (spouse and children) and how many credits they are taking. Number of credit taking Do you have a family Yes No Totals 12 68 181 18 Totals 125 74 24 96 120 217 283 500 199113 a. What is the probability that a student is without a family and taking 12 credits? b. What is the probability that a student has a family and taking 12 or more credits? c. Given that the student has a family, what is the chance of he/she will take 18 credits? d. Given that the student is taking 12 credits, what is the chance he/she doesn't have a family? 4. Scores on a certain test are normally distributed with a mean of 77.5 and a standard deviation of 9.3. a. What is the probability that an individual student will score more than 90? b, what scores represent the cutoff for the middle 95%? c. What proportion of the population will have a score between of 70 and 85?Explanation / Answer
Answer: 3:
(a)
Out of 500 students, 113 student do not have family and have credit score 12 so the required probabilty is
P(do not have family and credit score 12) = 113 /500 = 0.226
(b)
Out of 500 students, 68+24 = 92 students have family and have credit score 12 or more so the required probabilty is
P(have family and credit score 12 or more) = 92 /500 = 0.184
(c)
Out of 217 students with family, 24 have credit score 18 so the required probabilty is
P(credit score 18|have family) = 24 /217 = 0.1106
(d)
Out of 181 students who earned 12 credit, 113 do not have family so the required probabilty is
P(do not have family | credit score 12) = 113 /181 = 0.6243