How much undissolved sugar remains (HELP URGENT PLEASE)

Question

Suppose that sugar dissolving in water at room temperature is modeled by S(t)=Soe^kt where S(t) is the amount of undissolved sugar after t hours. If 100g of sugar was added to a sufficient volume of water and 55g dissolved in 2.5 hours, how much undissolved sugar remains after 6.75 hours?

Answer 1

45 =100e^2.5k

0.45 = e^2.5k

ln 0.45 = 2.5k

 

Solve for k.

That value in

S(t) = 100e^6.25k