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Finding the Fourth Proportional to 781.13, 1,077.64 and 485.89

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Solution

The fourth proportional to 781.13, 1,077.64 and 485.89 is: 670.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.13 : 1,077.64 = 485.89 : x
  2. Step 2: Convert to fraction form
    781.13/1,077.64 = 485.89/x
  3. Step 3: Cross multiply
    781.13x = 1,077.64 × 485.89
  4. Step 4: Simplify right side
    781.13x = 523,610.59
  5. Step 5: Solve for x
    x = 523,610.59/781.13
  6. Step 6: Final answer
    x = 670.32

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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.