Question

butirnu (20%) ) for each of the following 10 statements (2 marks each). of the Circle T (true) or F (false) xand y be two normal variables with mean values of μ. and μ. and standard deviationsoro, and ob respectively. The standard deviatice of y.yisơ (I)T F Let x be a normal variable with a mean of"nd standard deviation ofơ. The standard deviation of y-xls (2) TF 3 T F Ina Bemoulli sequence, the probability of a success event is ps the number of trials, N, until first success follows a geometric distribution with a mean value of E(CT)-1/p, which is also called "return period.' Hence return period refers to the mean interval between two success events. A success event may not occur after a period of ECT). For example, a flood of 100-ycar return period may not occur every 100 years. (4) T F For proposition A and evidence B, where P (A), the prior, is the initial degree of belief in A and P(AB), the postenior, evidence B, P (A |B) must be greater than P(A). is the degree of belief having accounted for B. Given the support of Suppose S is demand and R is capacity. The factor of safety in engineering design F is defined as FS- (mean of R) (mean of S). (S) T (6) T F Risk is a measure of the probability and severity of an adverse effect to life, health, property, or the environment. Risk is often expressed as R-HV E. If the annual failure probability (H) of physical facilities in a town is kept the same over a period of time, then the risk level of the town will remain constant during this period of time. 7TFNon-structural measures, such as early warning, land-use planning, public awareness, emergency preparedness and measures to pool and transfer the risks etc., are widely used for risk mitigation. The effectiveness of such measures may be quantified by the degrees they help decrease V and E (8) T F Vulnerability, or degree of damage, varies as hazard intensity and capacity of the element at risk change. (9) T FA fault tree consists of a few events illustrated in a systematic diagram, starting from a fault, while an event tree is a diagram to show the failure probability and consequence starting from an initiating event 10) T F In a Monte Carlo simulation, the number of simulations required to achievea specified accuracy (COV) of the calculated probability of failure pr is a function of pritself, among others

Answer 1

1. False. The standard deviation does not follow summation rule. The sd will be: sqrt(S1​​​^2 + S2^2)

2. False

3. True

4. False: It is not always true that P(A/B) must be greater than P(A)

5. True

6. False: Risk is dependent on V and E as well. Hence, it might change.

7. True

8. True

9. True

10. True