MongoDB query for deleting the lowest score from scores array with type of homework

Delete lowest score of homework type.js

{
	"_id" : 137,
	"name" : "Tamika Schildgen",
	"scores" : [
		{
			"type" : "exam",
			"score" : 4.433956226109692
		},
		{
			"type" : "quiz",
			"score" : 65.50313785402548
		},
		{
			"type" : "homework",
			"score" : 89.5950384993947
		},
		{
			"type" : "homework",
			"score" : 80.9348234982713
		}
	]
}

res=db.students.aggregate([{"$unwind":"$scores"},{"$match":{"scores.type":"homework"}},{"$group":{'_id':'$_id','minscore':{'$min':"$scores.score"}}}])
res.forEach(function(coll){db.students.update({'_id':coll._id}, {'$pull':{'scores':{'score':coll.minscore}}})})

db.students.aggregate( { '$unwind' : '$scores' } , { '$group' : { '_id' : '$_id' , 'average' : { $avg : '$scores.score' } } } , { '$sort' : { 'average' : -1 } } , { '$limit' : 1 } )