See the solutions to these problems just after the percentage calculator below.

Here are the solutions to the questions stated above:

Always use this formula to find a percentage:

^{%} / _{100} = ^{Part} / _{Whole} replace the given values:

^{3.9} / _{100} = ^{Part} / _{90.99}

Cross multiply:

3.9 x 90.99 = 100 x Part, or

354.861 = 100 x Part

Now, divide by 100 and get the answer:

Part = ^{354.861} / _{100} = 3.54861

Use again the same percentage formula:

^{%} / _{100} = ^{Part} / _{Whole} replace the given values:

^{%} / _{100} = ^{3.9} / _{90.99}

Cross multiply:

% x 90.99 = 3.9 x 100

Divide by 90.99 and get the percentage:

% = ^{3.9 x 100} / _{90.99} = 4.2861852950874%