# GATE | GATE-IT-2004 | Question 71

• Last Updated : 28 Jun, 2021

A software was tested using the error seeding strategy in which 20 errors were seeded in the code. When the code was tested using the complete test suite, 16 of the seeded errors were detected. The same test suite also detected 200 non-seeded errors. What is the estimated number of undetected errors in the code after this testing?
(A) 4
(B) 50
(C) 200
(D) 250

Explanation: Error seeding, as the name implies, seeds the code with some known errors. In other words, some artificial errors are introduced into the program artificially. The number of these seeded errors detected in the course of the standard testing procedure is determined. These values in conjunction with the number of unseeded errors detected can be used to predict:

• The number of errors remaining in the product.
• The effectiveness of the testing strategy.
Let N be the total number of defects in the system and let n of these defects be
found by testing.
Let S be the total number of seeded defects, and let s of these defects be found
during testing.
n/N = s/S
or
N = S × n/s
Defects still remaining after testing = N–n = n×(S – s)/s =200*(20-16)/16=50
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