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Finding the Fourth Proportional to 768.78, 1,151.75 and 421.59

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Solution

The fourth proportional to 768.78, 1,151.75 and 421.59 is: 631.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    768.78 : 1,151.75 = 421.59 : x
  2. Step 2: Convert to fraction form
    768.78/1,151.75 = 421.59/x
  3. Step 3: Cross multiply
    768.78x = 1,151.75 × 421.59
  4. Step 4: Simplify right side
    768.78x = 485,564.17
  5. Step 5: Solve for x
    x = 485,564.17/768.78
  6. Step 6: Final answer
    x = 631.60

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.