Doubt: 'Marked-up' price.

1. A product having CP of 100 is marked-up by 300%. SP?

2. Shopkeeper marked a product, 300% above the CP of 100. SP?

3. Ravi marked up a product at 300% above the CP of 100. SP?

I picked these phrases from the questions. In 2nd case they have taken SP as 300 and not 400 for the solution .

I think they all should be 400. If not, can someone plz clarify it for me?