You almost mentioned a good solution, use an array of objects like this to store the initial results:
let reactionTimeRecords = [{age: 15, house: "saturn", reactionTime: 10},{age: 14, house: "saturn", reactionTime: 11},{age: 14, house: "saturn", reactionTime: 8},{age: 15, house: "saturn", reactionTime: 8},{age: 14, house: "mars", reactionTime: 10},{age: 15, house: "mars", reactionTime: 9},{age: 14, house: "mars", reactionTime: 7},{age: 15, house: "mars", reactionTime: 10}]
then you can write a simple function to return the records based on what you passed in
const getScoresForHouse = houseName => {
return reactionTimeRecords.filter(record => record.house === houseName)
}