1) (5-8)*300，000，000=6*99. 125*n

N= 1, 513,240 copies.

1, 513,240 interest rate futures contracts should be sold.

2) In order to completely hedge the interest rate risk, that is, the duration is reduced to zero, then

(0-8)*300，000，000=6*99. 125*n]

N = 4,035,308 copies