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Finding the Fourth Proportional to 438.62, 661.84 and 421.74

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Solution

The fourth proportional to 438.62, 661.84 and 421.74 is: 636.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    438.62 : 661.84 = 421.74 : x
  2. Step 2: Convert to fraction form
    438.62/661.84 = 421.74/x
  3. Step 3: Cross multiply
    438.62x = 661.84 × 421.74
  4. Step 4: Simplify right side
    438.62x = 279,123.35
  5. Step 5: Solve for x
    x = 279,123.35/438.62
  6. Step 6: Final answer
    x = 636.37

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.