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Finding the Fourth Proportional to 1,217.25, 1,679.76 and 686.15

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Solution

The fourth proportional to 1,217.25, 1,679.76 and 686.15 is: 946.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,217.25 : 1,679.76 = 686.15 : x
  2. Step 2: Convert to fraction form
    1,217.25/1,679.76 = 686.15/x
  3. Step 3: Cross multiply
    1,217.25x = 1,679.76 × 686.15
  4. Step 4: Simplify right side
    1,217.25x = 1,152,558.93
  5. Step 5: Solve for x
    x = 1,152,558.93/1,217.25
  6. Step 6: Final answer
    x = 946.85

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.