testCaseCnt = int(input())

for i in range(0, testCaseCnt):
    daysInput = input()
    daysList = daysInput.split()
    availDays = int(daysList[0])
    rentDays = int(daysList[1])
    paysInput = input()
    pays = [int(n) for n in paysInput.split()]
    lowestPay = 101.0
    startIdxMaxValue = availDays - rentDays + 1
    for i in range(0, startIdxMaxValue):
        total = 0
        rentDaysMaxRange = availDays - i
        for j in range(rentDays, rentDaysMaxRange):
            if(total == 0):
                for k in range(0, j):
                    total += pays[k]
            else:
                total += pays[j-1]
            avgPay = total / j
            if(lowestPay > avgPay):
                lowestPay = avgPay
    print('{:.11f}'.format(lowestPay))