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Finding the Fourth Proportional to 999.61, 1,378.42 and 721.17

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Solution

The fourth proportional to 999.61, 1,378.42 and 721.17 is: 994.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    999.61 : 1,378.42 = 721.17 : x
  2. Step 2: Convert to fraction form
    999.61/1,378.42 = 721.17/x
  3. Step 3: Cross multiply
    999.61x = 1,378.42 × 721.17
  4. Step 4: Simplify right side
    999.61x = 994,073.35
  5. Step 5: Solve for x
    x = 994,073.35/999.61
  6. Step 6: Final answer
    x = 994.46

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.