Answer:
see explaination
Step-by-step explanation:
Given that we have;
Defects before testing = Defects planted = 5
Defects after testing = 20
Seeded defects found = 2
Real, non seeded defects = 18
Hence, Total number of defects = (defects planted / seeded defects found) * real, non seeded defects = (5/2)*18 = 45
Therefore, Estimated number of real defects still present = estimated total number of defects - number of real, non seeded defects found = 45-18 = 27