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Finding the Fourth Proportional to 1,223.43, 1,688.54 and 781.49

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Solution

The fourth proportional to 1,223.43, 1,688.54 and 781.49 is: 1,078.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,223.43 : 1,688.54 = 781.49 : x
  2. Step 2: Convert to fraction form
    1,223.43/1,688.54 = 781.49/x
  3. Step 3: Cross multiply
    1,223.43x = 1,688.54 × 781.49
  4. Step 4: Simplify right side
    1,223.43x = 1,319,564.77
  5. Step 5: Solve for x
    x = 1,319,564.77/1,223.43
  6. Step 6: Final answer
    x = 1,078.58

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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.