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Finding the Fourth Proportional to 1,129.80, 1,559.31 and 687.87

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Solution

The fourth proportional to 1,129.80, 1,559.31 and 687.87 is: 949.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,129.80 : 1,559.31 = 687.87 : x
  2. Step 2: Convert to fraction form
    1,129.80/1,559.31 = 687.87/x
  3. Step 3: Cross multiply
    1,129.80x = 1,559.31 × 687.87
  4. Step 4: Simplify right side
    1,129.80x = 1,072,602.57
  5. Step 5: Solve for x
    x = 1,072,602.57/1,129.80
  6. Step 6: Final answer
    x = 949.37

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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.