Consider a software program that is artificially seeded with $100$ faults. While testing this program, $159$ faults are detected, out of which $75$ faults are from those artificially seeded faults. Assuming that both real and seeded faults are of same nature and have same distribution, the estimated number of undetected real faults is _____________.
- $28$
- $175$
- $56$
- $84$
