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Finding the Fourth Proportional to 1,129.28, 1,557.77 and 687.12

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Solution

The fourth proportional to 1,129.28, 1,557.77 and 687.12 is: 947.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,129.28 : 1,557.77 = 687.12 : x
  2. Step 2: Convert to fraction form
    1,129.28/1,557.77 = 687.12/x
  3. Step 3: Cross multiply
    1,129.28x = 1,557.77 × 687.12
  4. Step 4: Simplify right side
    1,129.28x = 1,070,365.65
  5. Step 5: Solve for x
    x = 1,070,365.65/1,129.28
  6. Step 6: Final answer
    x = 947.83

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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.