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Finding the Fourth Proportional to 781.50, 1,078.62 and 486.71

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Solution

The fourth proportional to 781.50, 1,078.62 and 486.71 is: 671.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.50 : 1,078.62 = 486.71 : x
  2. Step 2: Convert to fraction form
    781.50/1,078.62 = 486.71/x
  3. Step 3: Cross multiply
    781.50x = 1,078.62 × 486.71
  4. Step 4: Simplify right side
    781.50x = 524,971.97
  5. Step 5: Solve for x
    x = 524,971.97/781.50
  6. Step 6: Final answer
    x = 671.75

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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.