TypeScript - weighted arithmetic mean

const calculateWeightedAverage = (values: number[], weights: number[]): number => {

    if (values.length !== weights.length) {

        throw new Error('Values and weights arrays must have same size.');

    }

    let a = 0;

    let b = 0;

    for (let i = 0; i < values.length; ++i) {

        const weight = weights[i];

        a += weight * values[i];

        b += weight;

    }

    return a / b;

};

​

​

// Usage example:

​

// Let's suppose we have: 4x 3.0, 9x 4.0 and 4x 5.0

​

const marks: number[] = [3.0, 4.0, 5.0];

const counts: number[] = [4, 9, 4];

​

const average: number = calculateWeightedAverage(marks, counts);

​

console.log(average);

4