People who have been exposed to Common Carolina Fever (CCF) will have a higher-than-normal death rate for 2 years following exposure to this disease. The death rate is 10% higher than normal during the first year, and 5% higher during the second year. After that the death rate returns to normal. Professor Smith, age x, has just been exposed to CCF. Calculate the reduction in his curtate expectation of life from normal, given the following information for normal lives:
qx = 0.07
qx+1 = 0.10
qx+2 = 0.11
ex+3 = 5

The answer is 0.0762. I think the problem is saying that after exposure, qx = 0.17 and qx+1 = 0.15. But I'm getting confused because I think the equation for curtate expectation of life has an infinity as the upper bound of the summation so I don't get how you can get an actual number answer ...