Acompound with a formula mass of 116.07 amu is found to be 41.39% carbon, 3.47% hydrogen and 55.14% oxygen by mass. find it molecular formula.

Start by finding the empirical formula (simplest). Turn the percentages to grams (imagine100g total) then convert to moles using the amu of each element.
Divide all moles by the smallest mole.

41.39 g C / 12 g/mol = 3.45 mol C
3.47 g H / 1 g/mol = 3.47 mol H
55.14 g O / 16 g/mol = 3.45 mol O

You can see that they are all about the same mole so if you divide them you get 1 of each. Empirical formula is then: CHO

Now, using the given mass 116.07 you solve for how many CHO there are.
CHO amu = 12+1+16 = 29 amu

116.07 amu / 29 amu = 4

molecular formula: