. 4. For a certain age at issue the following premiums are available for a special -year endowment insurance policy: The net single premium for a 1,000 endowment insurance, with return of the net single premium on death during the endowment period is 750. The net single premium for a 1,000 endowment insurance which pays double the face amount if and only if the insured survives n years, also with return of premium at death, is 800. What is the net single premium for a 1,700 n-year endowment insurance, without return of premium or double benefit