void recordLap(double val) {
  speeds[recordedLaps++] = val;
}

double averageSpeed() {
  double sum = 0;
  for (int i = 0; i < recordedLaps; i++) {
    sum = sum + speeds[i]; //  adds previous lap to sum
  }
  double average = sum / (double)recordedLaps;
  return average;
}