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Finding the Fourth Proportional to 661.86, 991.70 and 388.17

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Solution

The fourth proportional to 661.86, 991.70 and 388.17 is: 581.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.86 : 991.70 = 388.17 : x
  2. Step 2: Convert to fraction form
    661.86/991.70 = 388.17/x
  3. Step 3: Cross multiply
    661.86x = 991.70 × 388.17
  4. Step 4: Simplify right side
    661.86x = 384,948.19
  5. Step 5: Solve for x
    x = 384,948.19/661.86
  6. Step 6: Final answer
    x = 581.62

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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.