NO.PZ2020021205000061
问题如下:
A stock has an expected return of 15% and a volatility of 20%. The current price of the stock is USD 50, estimate 99% confidence for the price in six months.
选项:
解释:
Here, the time period is longer, and we should work
with lognormal distributions. From Equations (15.2) and
(15.3), the logarithm of the stock price has mean:
ln(50) + (0.15 - /2) x 0.5 = 3.9770
and standard deviation:
0.2* = 0.1414
We are 99% certain that:
3.9770 - (0.995) x 0.1414 < ln(Sr) < 3.9770
+ (0.995) X 0.1414
or
3.6127 < ln(Sr) < 4.3413
so that:
< Sr <
or
37.1
从将以来看,sigma*√T,应该是方差吧?我记得quant里学正态分布的时候,不是说这里写的是方差吗?怎么从答案解析来看,是标准差?