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Finding the Fourth Proportional to 1,187.12, 1,638.09 and 689.66

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Solution

The fourth proportional to 1,187.12, 1,638.09 and 689.66 is: 951.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.12 : 1,638.09 = 689.66 : x
  2. Step 2: Convert to fraction form
    1,187.12/1,638.09 = 689.66/x
  3. Step 3: Cross multiply
    1,187.12x = 1,638.09 × 689.66
  4. Step 4: Simplify right side
    1,187.12x = 1,129,716.96
  5. Step 5: Solve for x
    x = 1,129,716.96/1,187.12
  6. Step 6: Final answer
    x = 951.65

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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.