The data in Table E11-20 related diamond carats to purchase prices. It appeared in Singapore€™s Business Times, February 18, 2000.

(a) Graph the data. What is the relation between carat and price? Is there an outlier?

(b) What would you say to the person who purchased the diamond that was an outlier?

(c) Fit two regression models, one with all the data and the other with unusual data omitted. Estimate the slope coefficient with a 95% confidence interval in both cases. Comment on any difference.

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Carat Price Carat Price 1302 0.33 0.3 1327 0.33 0.3 1510 1098 1693 0.3 1510 0.34 1551 0.3 1260 0.34 0.31 1641 1410 0.34 0.34 1269 0.31 1555 0.31 1427 0.34 1316 0.31 1427 0.34 1222 1126 0.31 0.35 1738 1126 0.31 0.35 1593 1468 1447 0.32 0.35 0.32 1202 0.35 1255 0.36 1635 0.45 1572 0.46 0.36 1485 2942 0.37 1420 0.48 2532 0.37 3501 1420 0.5 0.4 1911 0.5 3501 0.4 1525 0.5 3501 3293 0.41 1956 0.5 1747 0.5 0.43 3016