AoPS_CP Week 7: Midterm Exam

lilijia Posted in AOPS_Counting_Probability，
28 October 2019
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Summary:

We took the midterm exam today, covering Chapters 1 to 6 (Countings). Congratulations to Annabelle, Jason, and Susan for being Top 3 this time! (Max is absent because of his contest). Keep up the good work!

If you feel upset about the score, do not give it up. What more important is to learn from the mistakes, and find the area of improvement. Look ahead. I am looking forward to your progress in the following months!

Here is the link to the answer key.

Here are some pictures of the board-writings in our second period (解题课), to help you make corrections.

Midterm Q15

The first picture is for Question 15. Thanks a lot to Annabelle for explaining it very clear to the class!!

Midterm Q18

The second picture is for Bonus Question 2. The star represents women, and the dot represents men. Please feel free to reach out if you have any questions.

Homework:

1. Make corrections to the test (Use a different color).

2. Preview Chapter 7: Introduction to Probability

 

See you next week!

SAT Math Week 8: Midterm Exam

lilijia Posted in SAT math，
28 October 2019
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Summary:

We took the Midterm Exam today — another practice SAT test.

Congratulations to Austin, Marina, Danielle, and Irene for making 700+ this time! (Kevin and Sarah were not here today). Also, it is so nice to see each student’s progress compared to their pre-test!

 

Homework:

1. Please make corrections to section 1 (we will hand out section 2 when we meet next week).

2. Finish #multiples of 3 on Page 57.

3. Preview Chapter 7: Constructing Models.

 

Errata (SAT Math: The Advanced Guide and Workbook)

Chapter 3 Exponential vs. Linear Growth, #3 (pg. 26): The answer explanation on page 260 has a typo. The rate should be 1 – 0.06 = 0.941−0.06=0.94.

Chapter 7 Constructing Models, #1 (pg. 47): The question should read “… and then lays \dfrac{x}{2}2x​ bricks per hour for 2y2y more hours.”

Chapter 21 Triangles, #14 (pg. 184): The diagram is drawn incorrectly, though it’s hard to tell. The diagram should be drawn so that triangle ABCABC is similar to triangle DEFDEF (and the sides should correspond).

Chapter 23 Trigonometry, #12 (pg. 207): The answer explanation on page 310 has a typo. In quadrant III, sine and cosine are both negatives (not positive).

Chapter 25 Probability, #10 (pg. 223): The first sentence of the question should read “A manufacturer uses two assembly lines to produce refrigerators.”

 

Please make those changes in the textbook 🙂 Thank you! See you all next week!

 

SAT Math Week 7

lilijia Posted in SAT math，
22 October 2019
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I am glad to see that each of our students is working hard in this class!! Proud of you!

Lesson review_Chapter 6 Expressions

1. Combine like terms

2. Expansion and factoring

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3. Combining fractions (find the common denominator)

4. Flipping (dividing) fractions

5. Splitting fractions

Homework:

1. Chapter Exercise: Page 44 Ex 1-13

2. Bonus Question

3. Make corrections to previous work, review, and get ready for the Midterm Exam on 10/27. We will have another practice test. Please bring your calculator (for section 2).

See you soon! Stay on the right track, and keep up the good work!

AOPS_CP Week 7

lilijia Posted in AOPS_Counting_Probability，
22 October 2019
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Welcome back, everyone!

Lesson Review_Chapter 6: Some Harder Counting Problems

Tips:

1. Plug in some numbers for variables, solve, and look for a pattern.

2. Try to solve a simpler version of the same problem.

3. Be flexible. Try different approaches.

Homework:

1. Page 109, Ex 6.8 to 6.12 (only 5 problems this week)

2. Review (pay special attention to the corrections to the previous problems), and get prepared for the midterm exam on 10/27. Good luck!

Course Roadmap:

In the first half of the fall semester, we have gone through the “counting part” (Can you remember the “counting strategies” we have learned so far? For example, the complementary method vs. the constructive method? Correcting the overcounting strategy, and so on). After the midterm exam, we will discuss “probabilities”. Have fun!

 

 

 

AOPS_CP Week 6

lilijia Posted in AOPS_Counting_Probability，
14 October 2019
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Chapter 5: More with Combinations

Lesson Review

Paths on a grid: The solution to the general problem is if you must take X right steps, and Y up steps then the number of routes is simply the ways of choosing where to take the right (or up) steps. i.e.

Annotation 2019-10-13 233851

Combine the counting techniques: complementary counting or casework; overcounting strategies, and so on.

Distinguishability matters (see section 5.4, examples of the balls and boxes).

 

Homework

Page 83, Ex 5.2.1 (classwork), 5.2.2, 5.2.3,

Page 88, Ex 5.3.1, 5.3.2, 5.3.3, 5.3.5

Page 91, Ex 5.4.1 (classwork), 5.4.2, 5.4.3

Page 93, Ex 5.10

Extra Resources

I am very glad to see that our students are making steady progress, especially in the quality of the homework. Keep up the good work!

Look forward to meeting you all next week. We miss our dear friends Annabelle, Jasmine, and Julia today:)

 

SAT Math Week 6

lilijia Posted in SAT math，
14 October 2019
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Chapter 5: Rates Lesson Review:

Today we went through the example problems in the textbook and discussed the worksheet that we did last week.

20191013 SAT_students 20191013 SAT_Michelle

Good job, students! (We miss you, Julia~~) Thank you, Michelle!!

Some formulas:

distance = rate (speed) * time, or rate = distance/time.

Pay attention to the conversion of units:

changing from one unit of measurement to another requires using a fractional conversion factor that tells the relationship between the two units so that like units cancel as in:

2 miles = 2 miles * 5280 feet/mile (conversion factor miles to feet) = 10560 feet

Homework:

  • Page 35-38: Chapter 5 Exercises
  • Correction of Worksheet 2 (ratio and rates problems)

See you next Sunday!

 

 

AOPS_CP Week 5

lilijia Posted in AOPS_Counting_Probability，
08 October 2019
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A warm welcome to our new friend, Susan!

Happy Birthday to Linda (10/5)!

 

Lesson review:

Chapter 4: Committees and Combinations

1. Choosing a “committee” (“combination”): the order doesn’t matter; while in a “permutation”, the order matters.

2. “n choose r”: combinations

3. Combinatorial identity:

slide_21

 

 

Homework:

  • Page 68: Ex 4.2.1, 4.2.3, 4.2.4
  • Page 72: Ex 4.3.2 to 4.3.5
  • Page 75: Ex 4.4.1 to 4.4.4

Extra Resource:

https://www.khanacademy.org/math/precalculus/x9e81a4f98389efdf:prob-comb#x9e81a4f98389efdf:combinations

Next week:

if you are not coming next Sunday, please inform me ahead. So that I can plan my lesson accordingly. Thanks 🙂

SAT Math Week 5

lilijia Posted in SAT math，
08 October 2019
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Unit 4: Proportion (Page 29-32)

This week we went through the homework for Unit 3 and made corrections in class. Thanks to our great TA Michelle for checking for us, and explaining the problems!

We learned Unit 4: Proportion.

Thanks to each of the students for contributing to the discussions!

Please focus on the relationships between length (1D), area (2D), and volume (3D) [Exam prep tips: to catch the key point, and “skip” the other “unrelated information”, can save us time in solving the problems]

  • length: a
  • area: a^2
  • volume: a^3

Homework: Worksheet

Next week is a long weekend. If you are not coming to school, please let me know:) Thank you!