Question

5. The student body of a large university consists of 60% female students. A random sample of 8 students is selected. What is the probability that among the students in the sample at least 6 are male? a. 0.0413 b. 0.0079 c. 0.0007 d. 0.0499

6. In a large class, suppose that your instructor tells you that you need to obtain a grade in the top 10% of your class to get an A on ExamX. From past experience, your instructor is able to say that the mean and standard deviation on ExamX will be 72 and 13, respectively, and that grades are distributed normally. What will be the minimum grade needed to obtain an A? a. 88.64 b. 55.36 c. 73.28 d. 75.32

7. The travel time for a businesswoman traveling between Dallas and Fort Worth is uniformly distributed between 40 and 90 minutes. The probability that her trip will take exactly 50 minutes is a. 1.00 b. 0.02 c. 0.06 d. 0.20 e. 0.00

Answer 1

5. Here p=0.40 is same for all, n=8 is constant, events are independent and only two outcomes

Hence all the properties of binomial are satisfied

So we will use excel formula of binomial

Hence correct answer is d. 0.0499

6. Here we need to find x such that P(X>x)=0.10

Using z table we have P(z>1.282)=0.10

So

Hence

So correct answer is a. 88.64