An urgent help for a question about birth rates in Markov chain

Hi,

I need an urgent help for a question. I don't have a background in Markov chain, so I would be very thankful if you can explain step-by-step.

The question is:
Give an example of birthrates λ(i) > 0 such that a birth process {X(t)} with birthrates λ(i), i ≥ 0 explodes on average at time t = 17.

Thanks in advance...

Solved

OK. I solved this problem by myself. There is no need help for this anymore

The solution is E(T)= Sum((1/lambda)^i)
E(T) is expected time, in this case 17,
Lambda is the birth rate, we will find it. and the Sum operation is "i" from 0 to infinite.

Sum operation equals to:
Sum((1/lambda)^i= 1/(1-lambda)

So 17=1/(1-lambda)

This gives the lambda as 16/17