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Unit 6 Combined Operations
49
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8. Castings are fi nished on a belt grinder. Twenty-fi ve castings are fi nished per
hour, and the grinder belt lasts 18 hours. If a higher-grade belt will last 30 hours,
how many more castings can be fi nished on one grinder belt, using the
higher-grade belt?
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9. If the lower-grade belt in problem 8 costs $7 and the higher grade belt costs $11,
which costs less per casting fi nished?
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10. How many of the parts shown in the fi gure below can be made from a piece
of stock 850 millimeters long?
7 mm
4 mm
4 mm
40 mm 30 mm
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