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Finding the Fourth Proportional to 787.65, 1,086.95 and 428.75

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Solution

The fourth proportional to 787.65, 1,086.95 and 428.75 is: 591.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    787.65 : 1,086.95 = 428.75 : x
  2. Step 2: Convert to fraction form
    787.65/1,086.95 = 428.75/x
  3. Step 3: Cross multiply
    787.65x = 1,086.95 × 428.75
  4. Step 4: Simplify right side
    787.65x = 466,022.23
  5. Step 5: Solve for x
    x = 466,022.23/787.65
  6. Step 6: Final answer
    x = 591.66

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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.