11. Where a member elects to use the minimum sum to purchase an approved annuity from an insurer, the Board shall, at the request of the member, forward to the insurer in payment for such purchase —
(a)
the whole or part of the amount maintained as the minimum sum; and
(b)
where the purchase price of the approved annuity exceeds the amount referred to in paragraph (a), any interest accrued on such amount.