Simplify the following text for a Grade 7 native English-speaking person.
Original: It was announced on 21 August 2010 by NDR that four of those cities had officially applied to host the 2011 Contest : Berlin , Hamburg , Hanover , and DÃ 1\/4 sseldorf .
Simplified: On 21 August 2010 , NDR announced that four of those cities had officially applied to host the 2011 Contest :