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Finding the Fourth Proportional to 661.12, 991.86 and 387.46

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Solution

The fourth proportional to 661.12, 991.86 and 387.46 is: 581.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.12 : 991.86 = 387.46 : x
  2. Step 2: Convert to fraction form
    661.12/991.86 = 387.46/x
  3. Step 3: Cross multiply
    661.12x = 991.86 × 387.46
  4. Step 4: Simplify right side
    661.12x = 384,301.12
  5. Step 5: Solve for x
    x = 384,301.12/661.12
  6. Step 6: Final answer
    x = 581.29

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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.