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Finding the Fourth Proportional to 780.98, 1,076.72 and 647.70

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Solution

The fourth proportional to 780.98, 1,076.72 and 647.70 is: 892.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.98 : 1,076.72 = 647.70 : x
  2. Step 2: Convert to fraction form
    780.98/1,076.72 = 647.70/x
  3. Step 3: Cross multiply
    780.98x = 1,076.72 × 647.70
  4. Step 4: Simplify right side
    780.98x = 697,388.31
  5. Step 5: Solve for x
    x = 697,388.31/780.98
  6. Step 6: Final answer
    x = 892.97

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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.