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Finding the Fourth Proportional to 781.90, 1,078.98 and 427.80

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Solution

The fourth proportional to 781.90, 1,078.98 and 427.80 is: 590.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.90 : 1,078.98 = 427.80 : x
  2. Step 2: Convert to fraction form
    781.90/1,078.98 = 427.80/x
  3. Step 3: Cross multiply
    781.90x = 1,078.98 × 427.80
  4. Step 4: Simplify right side
    781.90x = 461,587.64
  5. Step 5: Solve for x
    x = 461,587.64/781.90
  6. Step 6: Final answer
    x = 590.34

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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.