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MTH3251/ETC3510/ETC5351 Practice Exam Semester 1, 2019
发布时间:2022-06-15
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MTH3251/ETC3510/ETC5351
Practice Exam
Semester 1, 2019
Bt , t s 0, denotes the Brownian motion process started at zero.
1. (a) Derive the distribution, mean and variance of B2 + B1 .
(b) Find the mean of eB2+B1 .
(c) Find the conditional expectation E(eB +B2 1 }Bu , u - 1).
2. Let Xt solve the stochastic differential equation on the interval [0, T] dXt = 2Xt dt + 2dBt , with X0 = 1.
(a) Find XT .
Give the distribution, the mean and variance of XT . Justify your answer by stating properties of Ito integrals.
3. Let the market model in discrete time t = 0, 1, be given by stock S0 = 1, and S1 = ξ, where ξ has distribution P (ξ = 2) = 0.6 and P (ξ = 1/2) = 0.4, and savings account β0 = 1, β1 = β .
(a) State the First Fundamental theorem of asset pricing and apply it to derive the no-arbitrage condition for this model.
Show that discounted value of any portfolio is a martingale under the EMM Q
Prove that any claim can be replicated by a portfolio, and give such a portfolio. Specify it for the claim X = (4, 1), and give the price of this claim at time t = 0.
4. Assume the Black-Scholes market model for the stock price St and savings account βt , 0 - t - T.
(a) Give the definition of Black-Scholes model and show that it does not have arbitrage strategies. Hint: Use Girsanov Theorem.
(b) Let Vt , 0 - t - T, denote a self-financing replicating portfolio for a call option. Show that Vt = at St + bt βt for some processes at , bt . Then specify at , bt .
(c) Give the price at time t = 0 of a call option with exercise price K = 1 and expiration T = 1 for the model βt = 1, St = e2Bt . Your answer may include the values of the standard Normal distribution function.
5. The spot interest rate rt on interval [0, T] is modelled by drt = µdt + σdBt , where Bt is Brownian motion, and r0 , σ > 0. P (t, T) denotes the price at time t of the bond that pays $1 at time T, and βt denotes continuously compounding savings account with β0 = 1. The model is specified under the Equivalent Martingale Measure, so that P (t, T)/βt is a martingale for 0 - t - T.
(a) Show that βt = e 0(t) rsds and P (t, T) = E(e- tT rsds}>t ).
(b) Find the yield R(t, T). Hint: you can use 0a Bs ds has normal N(0, a3 /3) distribution.
The discrete time risk model is given by Un = 5 +
Yi , n = 0, 1, 2, 3 . . ., where Yi ’s are independent random variables with the Normal distribution with mean 1 and variance 2. Show that the probability that ruin occurs by the time n = 5 is less than e-5 . Justify all of your arguments.