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Finding the Fourth Proportional to 434.16, 645.72 and 421.20

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Solution

The fourth proportional to 434.16, 645.72 and 421.20 is: 626.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    434.16 : 645.72 = 421.20 : x
  2. Step 2: Convert to fraction form
    434.16/645.72 = 421.20/x
  3. Step 3: Cross multiply
    434.16x = 645.72 × 421.20
  4. Step 4: Simplify right side
    434.16x = 271,977.26
  5. Step 5: Solve for x
    x = 271,977.26/434.16
  6. Step 6: Final answer
    x = 626.44

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.