Here's the math(s):
90 images to make a 10 second video at a frame rate of 25 frames per second (fps) (in the UK) =
25 fps * 10 seconds = 250 frames
250 frames / 90 images = 2.778 frames per image
So each frame would need to be onscreen for just under three frames, which wouldn't look particularly smooth - for smooth motion you'd ideally have 25 images per second:
90 images / 25 frames per second = would only give you a total duration of 3.6 seconds of video, but it would be smooth.
This would look a lot smoother, but give you a shorter video.
Twixtor would attempt to interpolate between the frames, but works best on higher framerates than this - I suspect the results would look a bit unnatural (objects morphing out of nowhere).
The frame blending suggestion would probably look more natural, as it is just crossfading between each frame.
Hope this helps.