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Finding the Fourth Proportional to 811.92, 1,215.40 and 656.40

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Solution

The fourth proportional to 811.92, 1,215.40 and 656.40 is: 982.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.92 : 1,215.40 = 656.40 : x
  2. Step 2: Convert to fraction form
    811.92/1,215.40 = 656.40/x
  3. Step 3: Cross multiply
    811.92x = 1,215.40 × 656.40
  4. Step 4: Simplify right side
    811.92x = 797,788.56
  5. Step 5: Solve for x
    x = 797,788.56/811.92
  6. Step 6: Final answer
    x = 982.60

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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.