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Finding the Fourth Proportional to 787.16, 1,085.91 and 491.91

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Solution

The fourth proportional to 787.16, 1,085.91 and 491.91 is: 678.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    787.16 : 1,085.91 = 491.91 : x
  2. Step 2: Convert to fraction form
    787.16/1,085.91 = 491.91/x
  3. Step 3: Cross multiply
    787.16x = 1,085.91 × 491.91
  4. Step 4: Simplify right side
    787.16x = 534,169.99
  5. Step 5: Solve for x
    x = 534,169.99/787.16
  6. Step 6: Final answer
    x = 678.61

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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.