Pension Plans

Dear sir, in the defined benefit pension plan, how is the interest on corporate bonds accounted for, for both pension assets and pension liabilities? The questions in the revision kit are not consistent. For example, in one question for assets, they took assets at the beginning of the year * bond % and for liabilities they took (liabilities - benefits paid out) * bond % In another question, for assets they took (assets at beginning + benefits paid in - benefits paid out) * bond %. I'm not sure, but I think it has something to do with the benefits being paid at the beginning or at the end of the year. Could you kindly explain and give a formula that I can use for all the questions? Thank you sir