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Finding the Fourth Proportional to 438.40, 656.84 and 420.40

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Solution

The fourth proportional to 438.40, 656.84 and 420.40 is: 629.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    438.40 : 656.84 = 420.40 : x
  2. Step 2: Convert to fraction form
    438.40/656.84 = 420.40/x
  3. Step 3: Cross multiply
    438.40x = 656.84 × 420.40
  4. Step 4: Simplify right side
    438.40x = 276,135.54
  5. Step 5: Solve for x
    x = 276,135.54/438.40
  6. Step 6: Final answer
    x = 629.87

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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.