We allow a player to throw a dart 36 times and find the total
score for the player as well as the average score (the total
divided by 36).
Notice the average will be a number between 5 and 55.
Give a total score and an average that are likely for a player
with no special skill. Discuss your reasoning and show the work
leading to your proposed solution.
[These numbers are described as
the expected score and the expected average for the game.]
Suggestion: You might investigate the similar problem with 2 regions and 4 throws and then 4 regions and 16 throws as a way to begin thinking about the problem. How many darts do you think would fall in each region?
Extension: (Optional) If we measure the distance each of the 36 darts fall from the center, what do you think the average distance would be for a player with no special skills. Explain your reasoning, any connections with the expected average score in the game, and whether you have any belief about the accuracy of your response. (Is it an underestimate or an overestimate?)
For example, the context of a marsh land environment is familiar to many residents of Arcata. Suppose that water is flowing from a stream into a marsh for 5 hours at 30000 cubic feet per hour. What change might be expected in the amount of water in the marsh and in the height of the water along an embankment at the end of the five hours. It should seem reasonable to you that after five hours the marsh will contain an additional 150000 cubic feet of water. We need more information about the shape of the marsh to determine the change in the height along the embankment. In particular we would need more information about the surface area of the marsh and the grade (steepness) of the embankment. We would also want to know how fast the water is flowing out of the marsh.
Describe a context in a similar fashion related to the following three settings. Indicate some of the important variables and rates that would be of interest for this context. Discuss how knowing these rates can be used to determine other information related to the original variables.
1. Automobile and truck traffic on Highway 101 or at a
major traffic intersection.
2. A flu epidemic in a population of school children.
(Consider Susceptible, Infected, and Recovered members of the
population.)
3. A college class room. (You might consider such
variables as number of people present, temperature, or level of
sound.)
Extension or Substitute for one of the above: Describe a
context related to a setting connected to your major or
some personal interest.
A. Suppose f(x) = x ^{3 }+ Bx
^{2 } +2x + A.
Find A and B so that f(0) = 1 and f '(1) = 7.
B.Let P(t) = K + Lt + Mt^{2 }.
Find the coefficients K, L, and M so that P'(t) + P(t)
= t ^{2 } + t + 1 for all t.
Hint: Consider the equation when t = 0, t = 1 and t = -1.
Making Curves Fit together Smoothly.
One way to make a curve that passes through several points and
looks smooth is to draw several curves that are defined by a
small number of points and make sure that when the curves are
joined together they have the same tangent lines, making the
connections appear smooth.
C. Use curves defined by two quadratic poynomial functions
to make a single smooth curve that passes through the four
points, (-1,0), (0,0), (1,-2) and (2,0) as in the figure.
Discuss briefly the strategy you used to find your solution.
Suggestion: Let P(x) = Ax^{2} + Bx+
C and Q(x) = Dx^{2} + Ex+ F.
Have the pair of curves meet at (0,0).
D. Find a second pair of quadratic polynomials which can be
used to make a single smooth curve that passes through the
same four points. [Hint: Have the pair of curves meet at
(1,-2).]
E. Find a single cubic polynomial that passes through the same
four points. [Hint: What are the linear factors of such a
polynomial?]
C. Suppose you are given four constants
A, B, C, and D.
Let g(x) = (x - A)^{2} + (x - B)^{2}+
(x - C)^{2} + (x - D)^{2}. Using
calculus, for what value(s) of x does g(x) assume a minimum
value? Justify your answer briefly.
Generalize your result (if possible) for
1000 constants.
Assume P(x) is a solution to the differential equation P'(x) = 1/(1+x^{ }^{2}) with P(0) = 0.