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Finding the Fourth Proportional to 661.68, 991.98 and 387.90

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Solution

The fourth proportional to 661.68, 991.98 and 387.90 is: 581.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.68 : 991.98 = 387.90 : x
  2. Step 2: Convert to fraction form
    661.68/991.98 = 387.90/x
  3. Step 3: Cross multiply
    661.68x = 991.98 × 387.90
  4. Step 4: Simplify right side
    661.68x = 384,789.04
  5. Step 5: Solve for x
    x = 384,789.04/661.68
  6. Step 6: Final answer
    x = 581.53

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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.