export declare function sum(nums: number[]): number;
export declare function expected(nums: number[]): number;
export declare function variance(nums: number[], df: number): number;
export declare function covariance(X: number[], Y: number[]): number;
export declare function varSample(nums: number[]): number;
export declare function SDSample(nums: number[]): number;
export declare function varPopulation(nums: number[]): number;
export declare function SDPopulation(nums: number[]): number;