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Finding the Fourth Proportional to 787.86, 1,086.35 and 645.63

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Solution

The fourth proportional to 787.86, 1,086.35 and 645.63 is: 890.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    787.86 : 1,086.35 = 645.63 : x
  2. Step 2: Convert to fraction form
    787.86/1,086.35 = 645.63/x
  3. Step 3: Cross multiply
    787.86x = 1,086.35 × 645.63
  4. Step 4: Simplify right side
    787.86x = 701,380.15
  5. Step 5: Solve for x
    x = 701,380.15/787.86
  6. Step 6: Final answer
    x = 890.23

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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.