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Finding the Fourth Proportional to 781.39, 1,078.30 and 427.31

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Solution

The fourth proportional to 781.39, 1,078.30 and 427.31 is: 589.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.39 : 1,078.30 = 427.31 : x
  2. Step 2: Convert to fraction form
    781.39/1,078.30 = 427.31/x
  3. Step 3: Cross multiply
    781.39x = 1,078.30 × 427.31
  4. Step 4: Simplify right side
    781.39x = 460,766.24
  5. Step 5: Solve for x
    x = 460,766.24/781.39
  6. Step 6: Final answer
    x = 589.68

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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.