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Question Grade1 In a data set the following variables are recorded for a

large number of students : age (in years), gender (male/female), handedness (left/right/ambidextrous), height (cm).

Which of the variables age, gender, height and handedness are categorical and which are numerical?

Correct

Your Answer:

age and height are numerical and gender and handedness are categorical

Instructors Comment:

1.0

2 Draw a stem-and-leaf plot for the following data (on a piece of paper). How would the distribution be best described ?

 12, 12, 13, 14, 16, 18, 23, 23, 24, 25, 34, 67, 88, 177Correct

Your Answer: unimodal, right skewed with some apparent outliersInstructors Comment:

1.0

3 The average score for a class of 25 students was 75. If the 15 female students in the class averaged 70, then the male students in the class averaged : Correct

Your Answer: 82.5Instructors Comment:

1.0

4 Determine the sample mean and standard deviation of the following sample data (to 3dp) :

10, 20, 30, 45, 77, 89

 

 

Correct

Your Answer: mean is 45.167, standard deviation is 31.733Instructors Comment:

1.0

5 Which ones of the following is/are not included in a 5-number summary ?

mean, median, variance, standard deviation, range, maximum and minimum

Correct

Your Answer: mean, variance, standard deviation and rangeInstructors Comment:

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6 Let E and F be two independent events in a sample space with P(E) = 0.5 and P(F) = 0.7. Determine, if possible,  P(E or F). Correct

Your Answer: P(E or F) = 0.85

1.0

submit

Question GradeInstructors Comment:

7 Let A and B be two events in a sample space with P(A) = 0.2 and P(B) = 0.7. Determine, if possible, P(A and B). Correct

Your Answer:

P(A and B) cannot be determined from the information in the question

Instructors Comment:

1.0

8 Let A and B be two mutually exclusive events in a sample space with P(A) = 0.2 and P(B) = 0.3. Determine, if possible, P(A or B). Correct

Your Answer: P(A or B) = 0.5Instructors Comment:

1.0

9 Let C and D be two events in a sample space, with P(C) = 0.12, P(D) = 0.36 and P(C and D)  = 0.03. Determine  (if possible) the conditional probability P(C | D).

Correct

Your Answer: P(C | D) = 1/12Instructors Comment:

1.0

10 A quick and inexpensive blood test is introduced to screen for a disease which we will call D2.

When people who have the antibodies for D2 in their blood have the screening test, they have a 90% chance of getting a + result (and a 10% chance of a negative result).

When people who do not have the antibodies for D2 in their blood have the screening test, they have a 10% chance of getting a + result (and a 90% chance of a negative result).

Assume that 10% of the population have the antibodies in their blood.

A random person has a screening blood test. What is the probability that the test comes back positive?

Correct

Your Answer: 0.18Instructors Comment:

1.0