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Finding the Fourth Proportional to 1,129, 1,557.70 and 686.68

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Solution

The fourth proportional to 1,129, 1,557.70 and 686.68 is: 947.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,129 : 1,557.70 = 686.68 : x
  2. Step 2: Convert to fraction form
    1,129/1,557.70 = 686.68/x
  3. Step 3: Cross multiply
    1,129x = 1,557.70 × 686.68
  4. Step 4: Simplify right side
    1,129x = 1,069,641.44
  5. Step 5: Solve for x
    x = 1,069,641.44/1,129
  6. Step 6: Final answer
    x = 947.42

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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.