Math 7A, Final Exam Answers

Weidong Posted in Spring 2012, Teaching info
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You can find the answers to the final exam with the link below:

http://www.newtonchineseschool.org/teachers/wangweidong/Math7_2012_Spring_Fall_Asnwers.pdf

For those of you who have sent the tests to me, I have emailed them back to you, so you can talk about it with your kid and help them in the summer.

Enjoy the time off.

 

Math 7A, Lesson 16, 06/17/2012

Weidong Posted in Spring 2012, Teaching info
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This is our last class for Spring 2012 semester and we had our final test.

We stopped at 4:30 and I let students finish their exams at home, as I didn’t want to keep studnets until 5pm. After all, today is the last day of school!

Please finish the exam at home, scan it and email me. I will grade and email you back the score.

For those of you who could not attend the class today, drop me an email and I will send you the test to finish at home.

It’s been a pleasure to have you guys in my class. Keep up the good work, and have a wonderful summer.

 

 

Weidong Posted in Spring 2012, Teaching info
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We had review class today. Thanks to Ms. Cao, who covered for me today, as I needed to go to Support China Education report workshop. As you know, I, along with another teacher, took those 12 kids to China in April. Today they reported on their trip and learning experiece.

Please check the following link for the material we covered during the Spring semester:

http://blog.newtonchineseschool.org/wangweidong/teaching-plan-2/

We don’t have any specific review material, but students can go over their homework to refresh themselves.  We will have our final exam next week.

 

Math 7A, Lesson 14, 6/3/2012

Weidong Posted in Homework, Spring 2012, Teaching info
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We continued our lecture on Probabilities.

We introduced the important concepts of dependant events and independant events. Dependant event is a group of outcomes where the outcomes depend on each other, while an independant event is a group of outcomes where the outcomes do not depend on each other.

If A and B are two independant events, then the probability of A and B happening is:

P(A and B) = P(A) * P(B)

If A and B are two dependant events, then the probability of A and B happening is:

P( A and B) = P(A) * P(B after A)

Important to note is that for dependant events, when A happens, it changes the outcome space so P(B after A) is no longer the same as P(B), that is, we need to take into consideration about A’s happening.

We further talk about the two importance concepts of Permutations and Combinations.

A Combination is a group of outcomes where the order does not matter. For example, mixing two kinds of paints taken from 4 possible paints. Because of fixing effect, picking Red first then Blue has the same result of picking Blue first then Red. So here the order of picking does not matter.

A Permutation is an arrangement of outcomes in which the order does matter. For example, picking two paints out of 4 possible pains with one paint for the background and the other paint for the design. Order here matters.

We introduced that concept of factorial of a natural number where it is the product of itself and all the natural numbers less than it. So 5! = 5*4*3*2*1. And in particular, we define 0! = 1.

With that we have the formulae to calculate number of permutations of taking r things out of possible n things as:

nPr = n! / (n-r)!

And the number of combinations of taking r things out of possible n things is:

nCr = n! / [(n – r)! * r!]

Homework is as follows:

http://blog.newtonchineseschool.org/wangweidong/files/2012/06/Math7_Spring_HW_L14.pdf