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Finding the Fourth Proportional to 840.70, 1,255.38 and 686.92

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Solution

The fourth proportional to 840.70, 1,255.38 and 686.92 is: 1,025.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.70 : 1,255.38 = 686.92 : x
  2. Step 2: Convert to fraction form
    840.70/1,255.38 = 686.92/x
  3. Step 3: Cross multiply
    840.70x = 1,255.38 × 686.92
  4. Step 4: Simplify right side
    840.70x = 862,345.63
  5. Step 5: Solve for x
    x = 862,345.63/840.70
  6. Step 6: Final answer
    x = 1,025.75

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.