出人口自动控制系统也叫门禁系统，一般由（)等组成。A.计算机B．电子锁C.识别卡D．报警控制器E．探测

Rural环境下，Shadowing Standard Deviation通常选择()dB

A6

B7

C8

D10

iation of 20%, security 2 has expected return of 10% and standard deviation of 25%, and the correlation of security 1 with security 2 is 0.90. What are the expected return and standard deviation of portfolio with security 1 and security 2 when the weight of security 1 is -0.2？

A、The expected return is 0.09 and standard deviation is 0.265

B、The expected return is 0.075 and standard deviation is 0.288

C、The expected return is 0.12 and standard deviation is 0.225

D、The expected return is 0.09 and standard deviation is 0.275

iation of 20%, security 2 has expected return of 10% and standard deviation of 25%, and the correlation of security 1 with security 2 is 0.90. Calculating the expected return and standard deviation of portfolio with security 1 and security 2 when the weight of security 1 is 0.4.

A、The expected return is 0.09 and standard deviation is 0.265

B、The expected return is 0.075 and standard deviation is 0.288

C、The expected return is 0.12 and standard deviation is 0.225

D、The expected return is 0.12 and standard deviation is 0.265

iation of 20%, security 2 has expected return of 10% and standard deviation of 25%, and the correlation of security 1 with security 2 is 0.90. Calculating the expected return and standard deviation of portfolio with security 1 and security 2 when the weight of security 1 is 2.5.

A、The expected return is 0.15 and standard deviation is 0.265

B、The expected return is 0.2 and standard deviation is 0.023

C、The expected return is 0.225 and standard deviation is 0.25

D、The expected return is 0.225 and standard deviation is 0.23

iation of 20%, security 2 has expected return of 10% and standard deviation of 25%, and the correlation of security 1 with security 2 is 0.90. What are the expected return and standard deviation of portfolio with security 1 and security 2 when the weight of security 1 is -0.5？

A、The expected return is 0.09 and standard deviation is 0.265

B、The expected return is 0.075 and standard deviation is 0.288

C、The expected return is 0.12 and standard deviation is 0.225

D、The expected return is 0.12 and standard deviation is 0.265

iation of 20%, security 2 has expected return of 10% and standard deviation of 25%, and the correlation of security 1 with security 2 is 0.90. Calculating the expected return and standard deviation of portfolio with security 1 and security 2 when the weight of security 1 is 1.8.

A、The expected return is 0.09 and standard deviation is 0.265

B、The expected return is 0.19 and standard deviation is 0.288

C、The expected return is 0.2 and standard deviation is 0.23

D、The expected return is 0.19 and standard deviation is 0.2

iation of 20%, security 2 has expected return of 10% and standard deviation of 25%, and the correlation of security 1 with security 2 is 0.90. Calculating the expected return and standard deviation of portfolio with security 1 and security 2 when the weight of security 1 is 0.8.

A、The expected return is 0.14 and standard deviation is 0.265

B、The expected return is 0.14 and standard deviation is 0.206

C、The expected return is 0.12 and standard deviation is 0.225

D、The expected return is 0.12 and standard deviation is 0.265

n should be used if it is known. If the population standard deviation is not known, then it should be estimated with _______.

A、the sample variance

B、the sample standard deviation

C、the range

D、the mean

标准差(standard deviation)