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Finding the Fourth Proportional to 421.20, 623.70 and 421.20

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Solution

The fourth proportional to 421.20, 623.70 and 421.20 is: 623.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.20 : 623.70 = 421.20 : x
  2. Step 2: Convert to fraction form
    421.20/623.70 = 421.20/x
  3. Step 3: Cross multiply
    421.20x = 623.70 × 421.20
  4. Step 4: Simplify right side
    421.20x = 262,702.44
  5. Step 5: Solve for x
    x = 262,702.44/421.20
  6. Step 6: Final answer
    x = 623.70

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Why These Related Problems?

These problems maintain the same ratio (1.48) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.