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Finding the Fourth Proportional to 787.28, 1,087.28 and 721.66

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Solution

The fourth proportional to 787.28, 1,087.28 and 721.66 is: 996.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    787.28 : 1,087.28 = 721.66 : x
  2. Step 2: Convert to fraction form
    787.28/1,087.28 = 721.66/x
  3. Step 3: Cross multiply
    787.28x = 1,087.28 × 721.66
  4. Step 4: Simplify right side
    787.28x = 784,646.48
  5. Step 5: Solve for x
    x = 784,646.48/787.28
  6. Step 6: Final answer
    x = 996.65

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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.