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Finding the Fourth Proportional to 1,272.76, 1,909.85 and 687.75

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Solution

The fourth proportional to 1,272.76, 1,909.85 and 687.75 is: 1,032.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,272.76 : 1,909.85 = 687.75 : x
  2. Step 2: Convert to fraction form
    1,272.76/1,909.85 = 687.75/x
  3. Step 3: Cross multiply
    1,272.76x = 1,909.85 × 687.75
  4. Step 4: Simplify right side
    1,272.76x = 1,313,495.90
  5. Step 5: Solve for x
    x = 1,313,495.90/1,272.76
  6. Step 6: Final answer
    x = 1,032.01

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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.