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Finding the Fourth Proportional to 811.90, 1,215.45 and 487.90

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Solution

The fourth proportional to 811.90, 1,215.45 and 487.90 is: 730.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.90 : 1,215.45 = 487.90 : x
  2. Step 2: Convert to fraction form
    811.90/1,215.45 = 487.90/x
  3. Step 3: Cross multiply
    811.90x = 1,215.45 × 487.90
  4. Step 4: Simplify right side
    811.90x = 593,018.06
  5. Step 5: Solve for x
    x = 593,018.06/811.90
  6. Step 6: Final answer
    x = 730.41

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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.