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Finding the Fourth Proportional to 661.47, 991.85 and 387.65

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Solution

The fourth proportional to 661.47, 991.85 and 387.65 is: 581.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.47 : 991.85 = 387.65 : x
  2. Step 2: Convert to fraction form
    661.47/991.85 = 387.65/x
  3. Step 3: Cross multiply
    661.47x = 991.85 × 387.65
  4. Step 4: Simplify right side
    661.47x = 384,483.76
  5. Step 5: Solve for x
    x = 384,483.76/661.47
  6. Step 6: Final answer
    x = 581.26

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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.