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Finding the Fourth Proportional to 768.20, 1,152.30 and 421.40

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Solution

The fourth proportional to 768.20, 1,152.30 and 421.40 is: 632.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    768.20 : 1,152.30 = 421.40 : x
  2. Step 2: Convert to fraction form
    768.20/1,152.30 = 421.40/x
  3. Step 3: Cross multiply
    768.20x = 1,152.30 × 421.40
  4. Step 4: Simplify right side
    768.20x = 485,579.22
  5. Step 5: Solve for x
    x = 485,579.22/768.20
  6. Step 6: Final answer
    x = 632.10

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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.