还是不明白为什么不能直接相加

NO.PZ2016072602000032 问题如下 Your bank calculates a one-y 95% Vfor market risk, a one-ye99% Vfor operationrisk, ana one-ye99% Vfor cret risk. The measures are $100 million, $500 million, an$1 billion, respectively. Operationrisk is fineto inclu all risks thare not market risks ancret risks, anthese three categories are mutually uncorrelate The market risk Vassumes normally stributereturns, anthe bank expects to successful to keep its market risk Vthlevel for the whole year. Your boss wants your best estimate of a firmwi Vthe 1% level. Among the following choices, your best estimate is: $1.7 billion $1.94 billion $2.50 billion It is impossible to aggregate risks with fferent stributions having only this information. C is correct. First, we convert the ily Vthe 95% level to the same parameters the other. With the normality assumption, this is VARMKT = $100 x (2.326/ 1.645) 252\sqrt{252}252​ = $2,245. We then combine the three VARs taking the square root of the sum of squares, whigives V=$2,2452+$5002+$10002\sqrt{\$2,245^2+\$500^2+\$1000^2}$2,2452+$5002+$10002​ = $2,458. 如题

NO.PZ2016072602000032 问题如下 Your bank calculates a one-y 95% Vfor market risk, a one-ye99% Vfor operationrisk, ana one-ye99% Vfor cret risk. The measures are $100 million, $500 million, an$1 billion, respectively. Operationrisk is fineto inclu all risks thare not market risks ancret risks, anthese three categories are mutually uncorrelate The market risk Vassumes normally stributereturns, anthe bank expects to successful to keep its market risk Vthlevel for the whole year. Your boss wants your best estimate of a firmwi Vthe 1% level. Among the following choices, your best estimate is: $1.7 billion $1.94 billion $2.50 billion It is impossible to aggregate risks with fferent stributions having only this information. C is correct. First, we convert the ily Vthe 95% level to the same parameters the other. With the normality assumption, this is VARMKT = $100 x (2.326/ 1.645) 252\sqrt{252}252​ = $2,245. We then combine the three VARs taking the square root of the sum of squares, whigives V=$2,2452+$5002+$10002\sqrt{\$2,245^2+\$500^2+\$1000^2}$2,2452+$5002+$10002​ = $2,458. Market VAR不是要求10天的吗？怎么是求一年的了？

NO.PZ2016072602000032 $1.94 billion $2.50 billion It is impossible to aggregate risks with fferent stributions having only this information. C is correct. First, we convert the ily Vthe 95% level to the same parameters the other. With the normality assumption, this is VARMKT = $100 x (2.326/ 1.645) 252\sqrt{252}252 ​ = $2,245. We then combine the three VARs taking the square root of the sum of squares, whigives V= $2,2452+$5002+$10002\sqrt{\$2,245^2+\$500^2+\$1000^2}$2,2452+$5002+$10002 ​ = $2,458.为什么这里的mr or不乘以12。5，直接相加

Your bank calculates a one-y 95% Vfor market risk, a one-ye99% Vfor operationrisk, ana one-ye99% Vfor cret risk. The measures are $100 million, $500 million, an$1 billion, respectively. Operationrisk is fineto inclu all risks thare not market risks ancret risks, anthese three categories are mutually uncorrelate The market risk Vassumes normally stributereturns, anthe bank expects to successful to keep its market risk Vthlevel for the whole year. Your boss wants your best estimate of a firmwi Vthe 1% level. Among the following choices, your best estimate is: $1.7 billion $1.94 billion $2.50 billion It is impossible to aggregate risks with fferent stributions having only this information. C is correct. First, we convert the ily Vthe 95% level to the same parameters the other. With the normality assumption, this is VARMKT = $100 x (2.326/ 1.645) 252\sqrt{252}252 ​ = $2,245. We then combine the three VARs taking the square root of the sum of squares, whigives V= $2,2452+$5002+$10002\sqrt{\$2,245^2+\$500^2+\$1000^2}$2,2452+$5002+$10002 ​ = $2,458. 题目里也没说是求一年的var还是一天的var，不是time horizon没给吗?这种以后就默认是一天的？