The table below shows the results of inspecting 3,752 items.

To determine the cumulative percent of nonconformities by the end of the third operation using the given data, we sum the percent of nonconformities for the first three operations:

1st operation: 55.0%

2nd operation: 23.3%

3rd operation: 11.7%

Cumulative percent of nonconformities by the end of the third operation = 55.0% + 23.3% + 11.7% = 90.0% Hence, the correct answer is 90.0%.References:

ASQ Certified Quality Engineer Handbook.

Quality Management for Organizational Excellence by David L. Goetsch and Stanley Davis.