results = [
{id: 1, test: biology, candidates:[ {cid: 11},{cid: 12},{cid: 13}]},
{id: 2, test: chemistry, candidates:[ {cid: 15},{cid: 16},{cid: 17}]},
{id: 3, test: physics, candidates:[ {cid: 1},{cid: 6},{cid: 7}]}
];

var new_Result = results.map( function (subject) {
                    let promises = [];
                    if (subject.candidates && subject.candidates.length > 0)
                    {
                        subject.candidates.forEach( (element) => {
                            promises.push(mobileUtil. getTotalMarksPerCandidate(element));
                        });
                    }
                    return Promise.all(promises).then( result => {
                        console.log('Check this out', result);
                        subject.newCandidatelist = result;
                        return subject;
                    });
                });
                console.log('R: ', new_Result);
                resolve(params);

Thank you