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Finding the Fourth Proportional to 429.40, 645.45 and 421.30

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Solution

The fourth proportional to 429.40, 645.45 and 421.30 is: 633.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.40 : 645.45 = 421.30 : x
  2. Step 2: Convert to fraction form
    429.40/645.45 = 421.30/x
  3. Step 3: Cross multiply
    429.40x = 645.45 × 421.30
  4. Step 4: Simplify right side
    429.40x = 271,928.09
  5. Step 5: Solve for x
    x = 271,928.09/429.40
  6. Step 6: Final answer
    x = 633.27

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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.