Mobile app for multiple choice questions which will help in exam preparation

I am looking for experienced mobile app developers who can help me design a mobile solution for exam preparation. The app should be designed for Android platforms, and must be in the form of a native app. I already have an existing database of questions for the app, but i also want to have option to add remove more subjects and questions when i want to
so I would like the developers to implement it into their design. All developers should have pertinent mobile experience. The app should have multiple choice questions which will help users prepare for exams with ease. If you have experience designing such app, please share your portfolio and contact info. Thanks!