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} / _{400}

Cross multiply:

3.9 x 400 = 100 x Part, or

1560 = 100 x Part

Now, divide by 100 and get the answer:

Part = ^{1560} / _{100} = 15.6

Use again the same percentage formula:

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

^{%} / _{100} = ^{3.9} / _{400}

Cross multiply:

% x 400 = 3.9 x 100

Divide by 400 and get the percentage:

% = ^{3.9 x 100} / _{400} = 0.975%