请解释一下

Using historical data that was not publicly available at the time period being studied will have a sample with: A Look-ahead bias. B Sample selection bias C Data-mining bias. 这题答案对吗？不应该是前视偏差吧，他确实用的历史数据，只是不公开，能举几个具体例子吗？老师课上讲的范围很大，

A sample of 100 observations drawn from a normally distributed population has a sample mean of 12 and a sample standard deviation of 4. Using the extract from the z-distribution given below, find the 95% confidence interval for the population mean. The 95% confidence interval is closest to: A 7.840 to 27.683 B 11.216 to 12.784 C 11.340 to 12.660 什么时候用12+1.96*4，什么时候用12+1.96*4/100根号下呢？

老师，请问分母为什么n-1不是n呢？

Which of the following statements about the IRR and NPV methods is most accurate? A From the NPV, we can know how much the value of the firm has increased if you investment the project. B When evaluating mutually exclusive projects, the IRR and NPV methods always yield the same decisions. C When selecting between mutually exclusive projects, the project with the highest NPV should be accepted regardless of the sign of the NPV calculation. 这题c为什么不对？

An analyst determines that approximately 99% of the observations of daily sales for a company are within the interval from $230,000 to $480,000 and that daily sales for the company are normally distributed. If approximately 99% of all the observations fall in the interval μ±3σ, then using the approximate z-value rather than the precise table, the standard deviation of daily sales for the company is closest to: A $83,333. B $62,500. C $41,667. 一点思路都没有

An investor invested $10,000 into an account five years ago. Today, the account value is $18,682. What is the investor's annual rate of return on a continuously compounded basis? A 12.50%. B 11.33%. C 13.31%. 什么是 a continuously compounded basis?

A stock value is three times than last year. calculate the continuously compounded return over the period: A 18.2%. B 69.3%. C 110.0%. 这个用计算器怎么按？我假设起初是1，期末是3，3-1/1=2，2，2nd，ex次方，-1，最后等于6.389

An increase in which of the following items will most likely result in a wider confidence interval for the population mean? A Reliability factor B Degrees of freedom C Sample size 可以wider confidence interval的都有哪些？

The random variable X distributed normally with μ=0.196, and standard deviation = 0.1, what is the probability that X will be smaller than 0? A 0.097 B 0.032 C 0.025 这个没有表呀？怎么做？