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Finding the Fourth Proportional to 1,126.85, 1,689.12 and 638.87

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Solution

The fourth proportional to 1,126.85, 1,689.12 and 638.87 is: 957.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,126.85 : 1,689.12 = 638.87 : x
  2. Step 2: Convert to fraction form
    1,126.85/1,689.12 = 638.87/x
  3. Step 3: Cross multiply
    1,126.85x = 1,689.12 × 638.87
  4. Step 4: Simplify right side
    1,126.85x = 1,079,119.65
  5. Step 5: Solve for x
    x = 1,079,119.65/1,126.85
  6. Step 6: Final answer
    x = 957.65

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.