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Finding the Fourth Proportional to 1,217.77, 1,680.55 and 686.61

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Solution

The fourth proportional to 1,217.77, 1,680.55 and 686.61 is: 947.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,217.77 : 1,680.55 = 686.61 : x
  2. Step 2: Convert to fraction form
    1,217.77/1,680.55 = 686.61/x
  3. Step 3: Cross multiply
    1,217.77x = 1,680.55 × 686.61
  4. Step 4: Simplify right side
    1,217.77x = 1,153,880.72
  5. Step 5: Solve for x
    x = 1,153,880.72/1,217.77
  6. Step 6: Final answer
    x = 947.54

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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.