[{"avgLow":["1.19","1.24","1.29","1.34","1.39","1.44","1.49","1.54","1.59","1.64","1.69","1.74","1.79","1.84","1.89","1.94","1.99"],"avgHigh":["1.239","1.289","1.339","1.389","1.439","1.489","1.539","1.589","1.639","1.689","1.739","1.789","1.839","1.889","1.939","1.989","2.039"],"custFscPM":["0.01","0.02","0.03","0.04","0.05","0.06","0.07","0.08","0.09","0.10","0.11","0.12","0.13","0.14","0.15","0.16","0.17"]}]

db.collection.aggregate([{$project:{custFscPM:{$arrayElemAt:["$custFscPM",{$indexOfArray:["$avgLow",{$arrayElemAt:[{$filter:{input:"$avgLow",cond:{$gte:[{$toDouble:"$$this"},1.94]}}},0]}]}]}}}])