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Finding the Fourth Proportional to 1,187.10, 1,638.18 and 689.76

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Solution

The fourth proportional to 1,187.10, 1,638.18 and 689.76 is: 951.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.10 : 1,638.18 = 689.76 : x
  2. Step 2: Convert to fraction form
    1,187.10/1,638.18 = 689.76/x
  3. Step 3: Cross multiply
    1,187.10x = 1,638.18 × 689.76
  4. Step 4: Simplify right side
    1,187.10x = 1,129,951.04
  5. Step 5: Solve for x
    x = 1,129,951.04/1,187.10
  6. Step 6: Final answer
    x = 951.86

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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.