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Finding the Fourth Proportional to 778.21, 1,165.72 and 721.25

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Solution

The fourth proportional to 778.21, 1,165.72 and 721.25 is: 1,080.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    778.21 : 1,165.72 = 721.25 : x
  2. Step 2: Convert to fraction form
    778.21/1,165.72 = 721.25/x
  3. Step 3: Cross multiply
    778.21x = 1,165.72 × 721.25
  4. Step 4: Simplify right side
    778.21x = 840,778.17
  5. Step 5: Solve for x
    x = 840,778.17/778.21
  6. Step 6: Final answer
    x = 1,080.40

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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.