Question:
The control chart for a number of defects in a welded joint is
The control chart for a number of defects in a welded joint is
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Use a c-chart when counting number of defects; use a p-chart when counting fraction defective.
Updated On: Jan 13, 2026
- $\bar{X}$–chart
- R–chart
- c–chart
- p–chart
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The Correct Option is C
Solution and Explanation
Control charts are selected based on the type of quality data being monitored. When counting the number of defects or flaws appearing in a welded joint, the data belong to the class of count data, where the count may take any non-negative integer value. A c-chart is specifically used for monitoring the number of defects per inspection unit when the inspected area or opportunity is constant. Here, each welded joint represents one constant-size inspection unit, so a c-chart is the correct statistical tool. Other charts such as $\bar{X}$-chart and R-chart measure continuous variables like dimensions, while the p-chart is used for proportions of defective items, not the number of defects.
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