Name
_________________________________
I.D. Number
________________________
Project 2
Evaluation 32
Second Year Algebra 2 (MTHH 040 059)
Part B – Applications of Parabolas & Ellipses (possible 30 points)
Activity: You will answer the following questions. Clearly label the questions and show ALL
necessary steps.
1. A satellite dish is shaped like a parabola. The signals that originate from a satellite strike the
surface of the dish and are reflected to a single point, where the receiver is located. If the dish is
16 feet across at its opening and 5 feet deep at its center, at what position should the receiver be
placed? (2 pts)
!
2. A searchlight is shaped like a parabola. If the light source is located 3 feet from the base along
the axis of symmetry and the depth of the searchlight is 4 feet, what should the width of the
opening of the searchlight be? (3 pts)
3. The towers of a suspension bridge are 450 feet apart and 150 feet high from the roadway.
Cables are at a height of 25 feet above the roadway, midway between the towers, but gradually
get taller toward each end. Assume the x-axis is the roadway and the y-axis is the center of the
bridge, write an equation for the parabola. What is the height of the cable at a point 50 feet from
one of the towers? Round to the nearest whole number. (3 pts)
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MTHH 040
4. The parabolic arch shown in the figure is 45 feet above the water at the center and 180 feet wide
at the base. Will a boat that is 30 feet tall clear the arch 30 feet from the center? (Use water as
the x-axis.) (3 pts)
!
5. The Whispering Gallery in the Museum of Science and Industry in Chicago is 47.3 feet long and
is in the shape of an ellipse. The distance from the center of the room to the foci is 20.3 feet.
Find an equation that describes the shape of the room. How high is the room at its center? (3
pts)
6. A racetrack is in the shape of an ellipse, 100 feet long and 50 feet wide. What is the width of the
racetrack 10 feet from the vertex? Make sure to identify both endpoints of the new width. (3 pts)
7. A bridge is to be built in the shape of a parabola and is to have a span of 140 feet. The height of
the arch at a distance of 50 feet from the center is to be 20 feet. Find the height of the arch at its
center. (3 pts)
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MTHH 040
Part C – Martian Math (possible 12 points)
Activity: Even life has not yet been discovered on Mars, today we
know a lot of other things about the planet. Mars has a day about
25 hours long, a pattern of seasons similar to Earth’s, and polar
icecaps. Mars also has surface temperatures that rarely rise
above freezing and almost no oxygen in its atmosphere. Mars is
often called the Red Planet because red deserts cover its surface.
!
1. Mars travels in an elliptical orbit with the Sun
at one of its foci. Use the data from the
diagram to calculate a, b, and c of this
elliptical orbit. (4 pts)
2. Point P is the midpoint between Mars’ closest
and farthest distances to the Sun. Use your
values of a and b to write an equation of the
elliptical orbit of Mars relative to a coordinate
system drawn through point P (y-axis in
gray). Use distances in millions of kilometers.
(3 pts)
!
3. It is also useful to define Mars’ motion relative to the Sun. Imagine a new coordinate system (yaxis in black) with its origin at the center of the Sun. Rewrite your equation for the ellipse in this
new coordinate system. (3 pts)
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MTHH 040
4. Explain how the eccentricity of a planet’s orbit can affect its annual weather cycle. (2 pts)
Part D – Comparing Conditional Probability (possible 24 points)
Activity: You learned about Conditional
Probability in Lesson 8. Use your
knowledge to answer the following
questions using the given tree
diagram. For example to find P(P | D),
which is the probability that a person
with a disease will test positive for it
will be P(P | D) = 0.99.
!
Example: Find P(H | P).
P (H and P )
P (P )
Since P(H | P) = !
, find P(H and P) and P(P).
P(H and P) = 0.98 • 0.03
P(P) = P(D and P) or P(H and P)
= 0.0294
P (H and P )
P (P )
So P(H | P) = !
= 0.02 • 0.99 + 0.98 • 0.03 = 0.0492
Substitute.
0.0294
= ! 0.0492
≈ 0.598
Simplify.
About 60% of the people who test positive do not actually have the disease.
Use the tree diagram in the Example above to find each probability for 1–4. (2 pts each)
1.
P(N)
2.
P(H and N)
3.
P(H | N)
4.
P(D | N)
5. Explain the difference in the meaning between P(P | D) and P(D | P) for the test in the opening
example. Compare the values of P(P | D) and P(D | P). What is the best use for this test?
Explain. (2 pts)
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MTHH 040
6. You can take Bus 65 or Bus 79 to get to work. You take the first bus that arrives. The probability
that Bus 65 arrives first is 75%. There is a 40% chance that Bus 65 picks up passengers along
the way. There is a 60% chance that Bus 79 picks up passengers. Your bus picked up
passengers. What is the probability that it was Bus 65? (2 pts)
7. According to estimates from the federal government’s 2003 National Health Interview Survey,
based on face-to-face interviews in 16,677 households, about 58.2% of U.S. adults have both a
landline and a mobile phone, 2.8% have only a mobile phone service, but no landline, and 1.6%
have no telephone service at all.
a. Make a Venn diagram to help visualize the following probabilities: (2 pts)
b. What proportion of U.S. households can be reached by a landline call? (2 pts)
c. Are having a mobile phone and having a landline independent events? Explain. (2 pts)
8. Make a tree diagram based on the survey results below. (2 pts) Find P(a female respondent is
left-handed) and P(a respondent is both male and right-handed). (2 pts each)
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•
Of all the respondents, 17% are male.
•
Of the male respondents, 33% are left-handed.
•
Of female respondents, 90% are right-handed.
MTHH 040
Part E – Area Under the Curve (possible 14 points)
x2
−
1
e x
Activity: In the field of statistics the function f(x) = ! 2π
is used to model data like birth weight
or height. In Lesson 8, you learned how to calculate z-scores, which then those scores related to the
number of standard deviations that specific value was from the mean. Now, you will extend that
knowledge of z-scores and find the area under the graph of the function, f(x), to find probabilities.
Ex.
In a given population, the weights of babies are normally distributed about the mean, 3250 g.
The standard deviation is 500 g. Find the probability that a baby chosen at random weighs
from 2250 g to 4250 g.
Step 1
Find the z-scores of the lower and
upper limits.
Step 2
Enter f(x) =
−
1
e
2π
x2
x
as Y .
1
Adjust window values if needed.
value − mean
z-score = ! std. dev.
2250 − 3250
−1000
500
z =
= 500 = −2
1
4250 − 3250
1000
500
z =
= 500 = 2
!
2
Step 3
Use the CALC button and press 7 to access the ∫ f(x)dx feature. Move the cursor until the
lower limit is x = −2. Press ENTER. Then repeat steps with the cursor to find the upper
limit x = 2. Press ENTER.
!
The area under the curve from x = −2 to x = 2 is about 0.95. Therefore, the probability
that a baby weighs from 2250 g to 4250 g is about 95%.
Use the data and the function in the example above. Find the probability that the weight of a baby
chosen at random falls within each interval 1–4. (1.5 pts each)
1.
3150–4150 g
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2.
4300–4500 g
3.
less than 1800 g
4.
more than 4550 g
MTHH 040
5.
For questions 1–4, estimate the number of babies within each interval from a population of 2400
babies. Round to nearest whole number. You will have 4 answers total. (1 pt each)
answer for question 1 _____________
answer for question 2 _____________
answer for question 3 _____________
answer for question 4 _____________
6.
A battery company manufactures batteries having life spans that are normally distributed, with a
mean of 45 months and a standard deviation of 5 months. Find the probability that a battery
chosen at random will have each life span. (2 pts each)
a. 45–52 months
b. 48–50 months
This project can be submitted electronically. Check the Project page under “My Work” in the
UNHS online course management system or your enrollment information with your print
materials for more detailed instructions.
Project 2
MTHH 040

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