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Finding the Fourth Proportional to 781.53, 1,078.70 and 486.63

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Solution

The fourth proportional to 781.53, 1,078.70 and 486.63 is: 671.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.53 : 1,078.70 = 486.63 : x
  2. Step 2: Convert to fraction form
    781.53/1,078.70 = 486.63/x
  3. Step 3: Cross multiply
    781.53x = 1,078.70 × 486.63
  4. Step 4: Simplify right side
    781.53x = 524,925.35
  5. Step 5: Solve for x
    x = 524,925.35/781.53
  6. Step 6: Final answer
    x = 671.66

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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.