The formula for compounded continuously is :
[tex] A=Pe^{rt} [/tex]
Here the Amount triples , so let us say the new amount A=3P
[tex] 3P=Pe^{rt} [/tex]
Cancelling P from both sides we get,
[tex] 3=e^{rt} [/tex]
Now here we are given rate is 2.75% or 0.0275,
[tex] 3=e^{0.0275t} [/tex]
solving for t we get
t=39.95 years
