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Finding the Fourth Proportional to 2,187.20, 3,280.80 and 648

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Solution

The fourth proportional to 2,187.20, 3,280.80 and 648 is: 972

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,187.20 : 3,280.80 = 648 : x
  2. Step 2: Convert to fraction form
    2,187.20/3,280.80 = 648/x
  3. Step 3: Cross multiply
    2,187.20x = 3,280.80 × 648
  4. Step 4: Simplify right side
    2,187.20x = 2,125,958.40
  5. Step 5: Solve for x
    x = 2,125,958.40/2,187.20
  6. Step 6: Final answer
    x = 972

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.