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Finding the Fourth Proportional to 768.64, 1,153.10 and 421.78

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Solution

The fourth proportional to 768.64, 1,153.10 and 421.78 is: 632.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    768.64 : 1,153.10 = 421.78 : x
  2. Step 2: Convert to fraction form
    768.64/1,153.10 = 421.78/x
  3. Step 3: Cross multiply
    768.64x = 1,153.10 × 421.78
  4. Step 4: Simplify right side
    768.64x = 486,352.41
  5. Step 5: Solve for x
    x = 486,352.41/768.64
  6. Step 6: Final answer
    x = 632.75

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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.