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Finding the Fourth Proportional to 720.82, 1,078.39 and 515.49

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Solution

The fourth proportional to 720.82, 1,078.39 and 515.49 is: 771.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.82 : 1,078.39 = 515.49 : x
  2. Step 2: Convert to fraction form
    720.82/1,078.39 = 515.49/x
  3. Step 3: Cross multiply
    720.82x = 1,078.39 × 515.49
  4. Step 4: Simplify right side
    720.82x = 555,899.26
  5. Step 5: Solve for x
    x = 555,899.26/720.82
  6. Step 6: Final answer
    x = 771.20

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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.