Solution: (1) If the principal is X yuan, then x+x×2.88%×6= 10000,

Solution: x ≈ 8527.

Answer: Now, you have to deposit the principal of 8527 yuan.

(2) If the deposit principal is Y yuan, then (y+y? 2.7%×3)+(y+y？ 2.7%×3)×2.7%×3= 10000,

Solution: y ≈ 8558.

Answer: you need to deposit 8558 yuan.

(3)∵8527