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An online instructor sends updates to students via text. The probability model describes the number of text messages the instructor may send in a day. Texts Sent 0 1 2 3 4 5 P(X) 0.05 0.05 0.1 0.1 0.4 0.3 How many texts would you expect the instructor to send each day? 3.9 3.65 3.25 2.9 2.45 2. In 2016, the mean score on the AP Statistics exam was 2.80, with a standard deviation of 1.35. The mean score on the AP Calculus exam was 2.86, with a standard deviation of 1.55. What is the combined mean and standard deviation for these exams? Mean, 2.83; standard deviation, 0.2 Mean, 5.66; standard deviation, 2.9 Mean, 5.66; standard deviation, 2.055 Mean, 2.83; standard deviation, 2.9 Mean, 5.66; standard deviation, 4.225 3. Given the probability histogram pictured for a discrete random variable X, what is μx? 3.5 3.25 3.1 2.95 0.2 4. Let x denote the number of defective light bulbs in a randomly selected 20-count box from a local hardware store. The variable x has the following probability distribution: x 0 1 2 3 4 P(X) 0.28 0.37 0.22 0.08 0.05 Calculate and interpret σx. 0.22; if we were to select many boxes of bulbs randomly, we would expect about 0.22, on average, to contain defective bulbs 1.25; if we were to select many boxes of bulbs randomly, we would expect about 1.25, on average, to contain defective bulbs 0.28; if we were to select many boxes of bulbs randomly, we would expect about 0.28 to have no defects 1.099; if we were to select many boxes of bulbs randomly, the number of defective bulbs would typically vary about 1.099 from the mean 1.208; if we were to select many boxes of bulbs randomly, the number of defective bulbs would typically vary about 1.208 from the mean 5. The yearbook club surveyed 200 students about the number of courses in which they were enrolled and the length of time it took to get to school each day. Classify the random variables from the survey. Number of courses, discrete; travel time to school, discrete Number of courses, discrete; travel time to school, continuous Number of courses, continuous; travel time to school, discrete Number of courses, continuous; travel time to school, continuous Unable to determine from information given

An online instructor sends updates to students via text. The probability model describes the number of text messages the instructor may send in a day.

Texts Sent
0
1
2
3
4
5

P(X)
0.05
0.05
0.1
0.1
0.4
0.3

How many texts would you expect the instructor to send each day?
3.9 3.65 3.25 2.9 2.45

2. In 2016, the mean score on the AP Statistics exam was 2.80, with a standard deviation of 1.35. The mean score on the AP Calculus exam was 2.86, with a standard deviation of 1.55. What is the combined mean and standard deviation for these exams?
Mean, 2.83; standard deviation, 0.2 Mean, 5.66; standard deviation, 2.9 Mean, 5.66; standard deviation, 2.055 Mean, 2.83; standard deviation, 2.9 Mean, 5.66; standard deviation, 4.225

3. Given the probability histogram pictured for a discrete random variable X, what is μx?
3.5 3.25 3.1 2.95 0.2

4. Let x denote the number of defective light bulbs in a randomly selected 20-count box from a local hardware store. The variable x has the following probability distribution:
x
0
1
2
3
4

P(X)
0.28
0.37
0.22
0.08
0.05

Calculate and interpret σx.
0.22; if we were to select many boxes of bulbs randomly, we would expect about 0.22, on average, to contain defective bulbs
1.25; if we were to select many boxes of bulbs randomly, we would expect about 1.25, on average, to contain defective bulbs
0.28; if we were to select many boxes of bulbs randomly, we would expect about 0.28 to have no defects
1.099; if we were to select many boxes of bulbs randomly, the number of defective bulbs would typically vary about 1.099 from the mean
1.208; if we were to select many boxes of bulbs randomly, the number of defective bulbs would typically vary about 1.208 from the mean

5. The yearbook club surveyed 200 students about the number of courses in which they were enrolled and the length of time it took to get to school each day. Classify the random variables from the survey.
Number of courses, discrete; travel time to school, discrete
Number of courses, discrete; travel time to school, continuous
Number of courses, continuous; travel time to school, discrete
Number of courses, continuous; travel time to school, continuous
Unable to determine from information given

Added by Eric M.

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