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Finding the Fourth Proportional to 411.80, 617.70 and 387.80

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Solution

The fourth proportional to 411.80, 617.70 and 387.80 is: 581.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    411.80 : 617.70 = 387.80 : x
  2. Step 2: Convert to fraction form
    411.80/617.70 = 387.80/x
  3. Step 3: Cross multiply
    411.80x = 617.70 × 387.80
  4. Step 4: Simplify right side
    411.80x = 239,544.06
  5. Step 5: Solve for x
    x = 239,544.06/411.80
  6. Step 6: Final answer
    x = 581.70

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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.