What is the scientific notation for 3800

Icould really use some with this question.

5cakes cost 3.50 how much do 7 cakes cost

Arectangular lawn is 65 m long and 34 m wide. over time, people have walked along a diagonal as a shortcut and have created a straight path. what is the length of the path, to the nearest tenth of a meter? enter your answer as a deicmal in the box. m