Please help, question for loss at issue

I am doing the SOA old exam 2013 fall Question 12.



"company sells 15 years pure endowments of 10,000 to 500 lives. Independent future lifetime. The single premium for each pure endowment is determined by he equivalence principle. oL is the aggregate loss at issue random variable for there pure endowments"



I am having trouble with finding variance(oL).



I thought Loss at issue is only on interest assumption. Why we need to take variance for pure endowment 15_E_x..



thanks for your hlep~

Please help, question for loss at issue