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Finding the Fourth Proportional to 811.32, 1,213.68 and 687.15

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Solution

The fourth proportional to 811.32, 1,213.68 and 687.15 is: 1,027.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.32 : 1,213.68 = 687.15 : x
  2. Step 2: Convert to fraction form
    811.32/1,213.68 = 687.15/x
  3. Step 3: Cross multiply
    811.32x = 1,213.68 × 687.15
  4. Step 4: Simplify right side
    811.32x = 833,982.79
  5. Step 5: Solve for x
    x = 833,982.79/811.32
  6. Step 6: Final answer
    x = 1,027.94

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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.