Water drips from the nozzle of a shower onto the floor 200 cm below. The drops fall at regular (equal) intervals of time, the first drop striking the floor at the instant the fourth drop begins to fall. Find the locations (above the floor in cm) of the second and third drops when the first strikes the floor.

I think I understand how to do this question, but the system won't accept my answer.
I converted 200 cm to 2 m beforeI did anything else.
I started by finding the final velocity of the first drop using dx = (v^2iV^2)/(2a). I then used the velocity to find the total time of the first drop using dV = at. I got the time to be .23 seconds.
To find the position of the second and third drops i set up proportions for the times. For example the second drop was at .1533 seconds of its fall. I plugged that number into dx = iVt + 1/2(at^2) and got 75.11 (converted back to cm). I then subtracted that from 200 and got 124.883.
Does anyone see where I went wrong?