Query on HasMany reference

I've an entity model like this:

public class Request
{
    public virtual IList<Response> Responses { get; set; }
}

public class Response
{
    public virtual DateTime Timestamp { get; set; }
    public virtual bool Success { get; set; }
}

I'm trying to create a Query that will give me all Request where its latest Response (regarding to its Timestamp) is sucess. How can this be done?