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Finding the Fourth Proportional to 1,281.35, 1,767.91 and 721.79

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Solution

The fourth proportional to 1,281.35, 1,767.91 and 721.79 is: 995.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,281.35 : 1,767.91 = 721.79 : x
  2. Step 2: Convert to fraction form
    1,281.35/1,767.91 = 721.79/x
  3. Step 3: Cross multiply
    1,281.35x = 1,767.91 × 721.79
  4. Step 4: Simplify right side
    1,281.35x = 1,276,059.76
  5. Step 5: Solve for x
    x = 1,276,059.76/1,281.35
  6. Step 6: Final answer
    x = 995.87

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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.