21. A computer assembling company buys all its memory cards from three manufacturers M1,M2,M3. The quality control manager of the company decided to learn more about the quality of the memory cards purchased from the three manufacturers, and thus took a random sample of 500 cards from the shipments received from each manufacturer and classified them according to whether the card is defective or non-defective. The results are shown below. Test, at the 5% level of significance, the hypothesis that the quality of the memory cards is independent of the manufacturer.

590 13 Analysis of Categorical Data M 1 M 2 M 3 Defective 32 52 28 Nondefective 468 448 472