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Finding the Fourth Proportional to 1,217.70, 1,680.31 and 686.61

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Solution

The fourth proportional to 1,217.70, 1,680.31 and 686.61 is: 947.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,217.70 : 1,680.31 = 686.61 : x
  2. Step 2: Convert to fraction form
    1,217.70/1,680.31 = 686.61/x
  3. Step 3: Cross multiply
    1,217.70x = 1,680.31 × 686.61
  4. Step 4: Simplify right side
    1,217.70x = 1,153,718.51
  5. Step 5: Solve for x
    x = 1,153,718.51/1,217.70
  6. Step 6: Final answer
    x = 947.46

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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.