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Finding the Fourth Proportional to 661.05, 991.71 and 387.18

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Solution

The fourth proportional to 661.05, 991.71 and 387.18 is: 580.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.05 : 991.71 = 387.18 : x
  2. Step 2: Convert to fraction form
    661.05/991.71 = 387.18/x
  3. Step 3: Cross multiply
    661.05x = 991.71 × 387.18
  4. Step 4: Simplify right side
    661.05x = 383,970.28
  5. Step 5: Solve for x
    x = 383,970.28/661.05
  6. Step 6: Final answer
    x = 580.85

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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.