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Finding the Fourth Proportional to 1,129.70, 1,559.12 and 687.66

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Solution

The fourth proportional to 1,129.70, 1,559.12 and 687.66 is: 949.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,129.70 : 1,559.12 = 687.66 : x
  2. Step 2: Convert to fraction form
    1,129.70/1,559.12 = 687.66/x
  3. Step 3: Cross multiply
    1,129.70x = 1,559.12 × 687.66
  4. Step 4: Simplify right side
    1,129.70x = 1,072,141.02
  5. Step 5: Solve for x
    x = 1,072,141.02/1,129.70
  6. Step 6: Final answer
    x = 949.05

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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.