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Finding the Fourth Proportional to 421.82, 628.75 and 389.01

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Solution

The fourth proportional to 421.82, 628.75 and 389.01 is: 579.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.82 : 628.75 = 389.01 : x
  2. Step 2: Convert to fraction form
    421.82/628.75 = 389.01/x
  3. Step 3: Cross multiply
    421.82x = 628.75 × 389.01
  4. Step 4: Simplify right side
    421.82x = 244,590.04
  5. Step 5: Solve for x
    x = 244,590.04/421.82
  6. Step 6: Final answer
    x = 579.84

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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.