import { IterableX } from '../../iterable/iterablex';
export declare function averageProto(this: IterableX<number>, selector?: (x: number) => number): number;
export declare function averageProto<T>(this: IterableX<T>, selector?: (x: T) => number): number;
declare module '../../iterable/iterablex' {
    interface IterableX<T> {
        average: typeof averageProto;
    }
}