So for these problems, we are going to need to use the formula
M = image height / object height
in this case, M = 16.6 and the image height is 5.3 cm
Plugging in the numbers, we get 16.6 = 5.3 cm / object height
object height = 5.3/16.6
the object is .3192... cm
rounding to 2 decimal places, the answer is .32 cm