MATH 273 Life Insurance I
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JANUARY 2017 EXAMINATIONS
MATH 273
Life Insurance I
1. (a) Demonstrate that e北 = p北 (1 + e北+1 ) [5 marks] (b) Give the formula which defines each of the following actuarial symbols.
[5 marks]
(ii) µ北
(c) You are given:
(i) A40:12 = 0.38 (ii) A40 = 0.34
(iii) A40(1):12 = 0.26
Calculate A52
(d) A 10-year endowment insurance is issued to a life aged 55 with a sum insured of £100,000 payable immediately on death, or at the end of the term, whichever is sooner. Level premiums are paid continuously at the annual rate of £7,000 throughout the term.
(i) Write down the Thiele differential equation for t V for 0 < t < 10. [3 marks]
(ii) Explain how you would evaluate policy values with continuous cash- flows. [2 marks]
2. (a) Let S0 (x) = 1 − (x/100)2 , for 0 ≤ x ≤ 100, where S0 (x) represents the survival function that a newborn survives beyond age x.
(i) Explain why the function S0 (x) is a survival function. [3 marks]
(ii) Use the survival function to calculate:
5p50 , 5|10q30 and e˚70 . [7 marks]
(iii) Do you think it is feasible to use this lifetime distribution to model human mortality? Explain your answer. [3 marks]
(b) Consider a mortality model with a one-year select period.
(i) Demonstrate that:
[北]:n = 1 + vp[北] 北+1:n −1 [4 marks]
(ii) You are given that 北:n = 21.5, [北]:n = 22.1 and p[北] = (1 + b)p北
for some constant b. Calculate b. [3 marks]
3. (a) Give a formula which defines each of the following actuarial symbols. Explain what each symbol measures.
(i) (I¯)北:n
(ii) (I¯A)北:n [6 marks]
(b) Explain why with a positive interest rate:
(北 ≥ (北:(1) [4 marks]
(c) On 1 January 2016 a life insurance company issued 500 identical whole life policies to lives aged exactly 65. The sum insured, per policy, payable at the end of the year of death, is £25,000 and level premiums P are payable annually throughout life.
Let L0 be the future loss random variable denoting the present value, at 1 January 2016, of the loss from this group of policies.
(i) Derive the expressions, in terms of P, for E[L0] and Var[L0]. [6 marks]
(ii) Give an expression for the probability that L0 is less than (−10P). [4 marks]
4. On 1 January 2014 a life insurance company issued 1,000 identical special endowment insurance policies to select lives then aged 50. Each policy has a term of 15 years and level premiums are payable annually throughout the policy term. On death within the policy term, a sum insured of £100,000 is paid. On survival to the end of the term, a sum insured of £75,000 is paid.
The premium is calculated using the AM92 select tables and assuming
• Interest: 4%
• Initial expenses: 50% of the first gross premium
• Renewal expenses: 5% of gross premium after the first
(i) Show that the annual premium for each policy is £4,302. [3 marks]
(ii) Calculate the gross policy value per policy in force at the start of 2016, just before the premium due is paid. [3 marks]
(iii) Calculate the asset share for each policy at the start of 2016. [5 marks]
(iv) Comment your answers to parts (ii) and (iii). [4 marks]
(v) There were 995 policies in force on 1 January 2016. During 2016 there were 2 actual deaths, the actual interest rate earned by the company was 3.8% and the expenses were 7%. Calculate the profit or loss in 2016 for this group of policies. [5 marks]
5. (a) (i) Suppose that the force of mortality is constant between ages x and x +1. Show that for 0 ≤ t ≤ 1
tpx = (px )t [3 marks]
(ii) Calculate 20.5p45.4 using AM92 ultimate and assuming uniform dis- tribution of deaths (UDD) between integer ages. [3 marks]
(iii) Calculate 15.7|3.3 q60 using AM92 ultimate and assuming constant force of mortality between integer ages. [4 marks]
(b) A life aged 35 buys a with-profit whole life insurance. The basic sum insured, payable at the end of year of death, is £25,000 and the level of monthly premiums are payable for at most 30 years. The premium is calculated using the AM92 ultimate mortality tables and assuming
• Interest: 6%
• Expenses: 15% of all premiums
• Bonuses: A compound reversionary bonus at 1.93208% each year, vesting on each policy anniversary.
The bonuses are included in the premium basis.
(i) Specify the value of j so that the expected present value of the benefit can be written:
50, 000A35|j [5 marks]
(ii) Calculate the monthly premium. [5 marks]
2023-01-10