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Finding the Fourth Proportional to 921.70, 1,381.35 and 664.90

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Solution

The fourth proportional to 921.70, 1,381.35 and 664.90 is: 996.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.70 : 1,381.35 = 664.90 : x
  2. Step 2: Convert to fraction form
    921.70/1,381.35 = 664.90/x
  3. Step 3: Cross multiply
    921.70x = 1,381.35 × 664.90
  4. Step 4: Simplify right side
    921.70x = 918,459.62
  5. Step 5: Solve for x
    x = 918,459.62/921.70
  6. Step 6: Final answer
    x = 996.48

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.