In West Texas, water is extremely important. The following data represent pH levels in ground water for a random sample of 102 West Texas wells. A pH less than 7 is acidic and a pH above 7 is alkaline. Scanning the data, you can see that water in this region tends to be hard (alkaline). Too high a pH means the water is unusable or needs expensive treatment to make it usable. (A) Look at a stem-and-leaf plot of the data. Use five lines per stem so that leaf values 0 and 1 str on one line, 2 and 3 are on the next line, 4 and 5 are on the next, 6 and 7 are on the next, and 8 and 9 are on the last line of he stem. Are there any unusually high or low pH levels in this sample of wells? a. there are no large gaps on either side of the plot, indicating that there are no outliers. there are no unusually high or low ph levels in the sample. b. there is a large gap beside some outliers on the right side of the plot. there are unusually high pH levels in the sample. c. there is a large gap beside some outliers on the left side of the plot. there are unusually low pH levels in the sample. d. there is a large gap beside some outliers on both sides of the plot. there are unusually high and low ph levels in the sample. (B) How many wells are neutral (pH of 7)?
Continuous Probability Distributions
Probability distributions are of two types, which are continuous probability distributions and discrete probability distributions. A continuous probability distribution contains an infinite number of values. For example, if time is infinite: you could count from 0 to a trillion seconds, billion seconds, so on indefinitely. A discrete probability distribution consists of only a countable set of possible values.
Normal Distribution
Suppose we had to design a bathroom weighing scale, how would we decide what should be the range of the weighing machine? Would we take the highest recorded human weight in history and use that as the upper limit for our weighing scale? This may not be a great idea as the sensitivity of the scale would get reduced if the range is too large. At the same time, if we keep the upper limit too low, it may not be usable for a large percentage of the population!
In West Texas, water is extremely important. The following data represent pH levels in ground water for a random sample of 102 West Texas wells. A pH less than 7 is acidic and a pH above 7 is alkaline. Scanning the data, you can see that water in this region tends to be hard (alkaline). Too high a pH means the water is unusable or needs expensive treatment to make it usable.
(A) Look at a stem-and-leaf plot of the data. Use five lines per stem so that leaf values 0 and 1 str on one line, 2 and 3 are on the next line, 4 and 5 are on the next, 6 and 7 are on the next, and 8 and 9 are on the last line of he stem. Are there any unusually high or low pH levels in this sample of wells?
a. there are no large gaps on either side of the plot, indicating that there are no outliers. there are no unusually high or low ph levels in the sample.
b. there is a large gap beside some outliers on the right side of the plot. there are unusually high pH levels in the sample.
c. there is a large gap beside some outliers on the left side of the plot. there are unusually low pH levels in the sample.
d. there is a large gap beside some outliers on both sides of the plot. there are unusually high and low ph levels in the sample.
(B) How many wells are neutral (pH of 7)?
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