Suppose that when the pH of a certain chemical compound is 5.00, the pH measured by a randomly selected beginning chemistry student is a random variable with mean 5.00 and standard deviation .2. A large batch of the compound is subdivided and a sample given to each student in a morning lab and each student in an afternoon lab. Let X = the aver- age pH as determined by the morning students and Y = the average pH as determined by the afternoon students. a. If pH is a normally distributed random variable and there are 25 students in each lab, compute P1-.1 X - Y .12 . (Hint: X - Y is a linear combination of normal variables, so it is normally distributed. Compute mX -Y and sX -Y .)
b. If there are 36 students in each lab, but pH deter- minations are not assumed normal, calculate (ap- proximately) P1-.1 X - Y .12 .

Lindsay is creating a bridge out of dried pasta and glue. in her plans, she sketches the graph to determine the lengths of the noodles, in centimeters, needed for the arch to increase the length of the bridge in 1 centimeter increments. which function did lindsay use to create her design? f(x) = (x – 5)2 + 8 f(x) = –(x + 5)2 + 8 f(x) = 0.5(x + 5)2 + 8 f(x) = –0.5(x – 5)2 + 8

Part one: measurements 1. measure your own height and arm span (from finger-tip to finger-tip) in inches. you will likely need some from a parent, guardian, or sibling to get accurate measurements. record your measurements on the "data record" document. use the "data record" to you complete part two of this project. name relationship to student x height in inches y arm span in inches archie dad 72 72 ginelle mom 65 66 sarah sister 64 65 meleah sister 66 3/4 67 rachel sister 53 1/2 53 emily auntie 66 1/2 66 hannah myself 66 1/2 69 part two: representation of data with plots 1. using graphing software of your choice, create a scatter plot of your data. predict the line of best fit, and sketch it on your graph. part three: the line of best fit include your scatter plot and the answers to the following questions in your word processing document 1. 1. which variable did you plot on the x-axis, and which variable did you plot on the y-axis? explain why you assigned the variables in that way. 2. write the equation of the line of best fit using the slope-intercept formula $y = mx + b$. show all your work, including the points used to determine the slope and how the equation was determined. 3. what does the slope of the line represent within the context of your graph? what does the y-intercept represent? 5. use the line of best fit to you to describe the data correlation.

Which of the following is most likely the next step in the series? a3z, b6y, c9x, d12w, е15v, f18u