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Finding the Fourth Proportional to 1,187.82, 1,638.87 and 721.74

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Solution

The fourth proportional to 1,187.82, 1,638.87 and 721.74 is: 995.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.82 : 1,638.87 = 721.74 : x
  2. Step 2: Convert to fraction form
    1,187.82/1,638.87 = 721.74/x
  3. Step 3: Cross multiply
    1,187.82x = 1,638.87 × 721.74
  4. Step 4: Simplify right side
    1,187.82x = 1,182,838.03
  5. Step 5: Solve for x
    x = 1,182,838.03/1,187.82
  6. Step 6: Final answer
    x = 995.81

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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.