"The consideration above is exactly the same as the argument leading to the definition of expection in previous chapter. In fact, E(X) = 10, 000, 000P(X = +10, 000, 000)− 5P(X = −5) ≈ −4.285 That is, if we play the game many times, we should expect to lost roughly $4,285 per game. " 4.285=4,285 ?!
回覆 1# Au Yeung Yat Apparently this is a typo. We will contact the maintainer of the question pool to follow up the case. -- by Guo Xin
Also,(Level 3 Complex Number, Ch.3 Theorem 3.3) "Please be reminded again that, we are using radians(rad) as the measure unit for all angels and arguments."
回覆 5# Mathematics tutor 1 "...we are using radians(rad) as the measure unit for all angels and arguments."
回覆 6# Au Yeung Yat Although I still am confused about your question, I guess what you asked is "how can radian be the measure of an angle?", is that correct? Radian is used to measure the angle. There is no unit, and if used, the trigonometric functions enjoy good Taylor expansions. Approximately 1 rad equals 57.29578 degrees. For details, see the wikipedia page https://en.wikipedia.org/wiki/Radian, or some standard middle school mathematics textbooks. Please do not hesitate to let me know if this still does not answer your question. -- by Guo Xin
回覆 8# Au Yeung Yat Thank you for the kind comment and your point is absolutely right. Let me forward the comment to the forum maintainer to follow up. -- by Guo Xin
回覆 8# Au Yeung Yat Typo reported and I got the reply from the Gifted Education Section that the typo will be fixed in the coming revision of content. Many thanks for reporting. -- by Guo Xin