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Finding the Fourth Proportional to 420.12, 629.51 and 387.05

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Solution

The fourth proportional to 420.12, 629.51 and 387.05 is: 579.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.12 : 629.51 = 387.05 : x
  2. Step 2: Convert to fraction form
    420.12/629.51 = 387.05/x
  3. Step 3: Cross multiply
    420.12x = 629.51 × 387.05
  4. Step 4: Simplify right side
    420.12x = 243,646.76
  5. Step 5: Solve for x
    x = 243,646.76/420.12
  6. Step 6: Final answer
    x = 579.95

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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.