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Finding the Fourth Proportional to 661.15, 991.78 and 198.92

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Solution

The fourth proportional to 661.15, 991.78 and 198.92 is: 298.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.15 : 991.78 = 198.92 : x
  2. Step 2: Convert to fraction form
    661.15/991.78 = 198.92/x
  3. Step 3: Cross multiply
    661.15x = 991.78 × 198.92
  4. Step 4: Simplify right side
    661.15x = 197,284.88
  5. Step 5: Solve for x
    x = 197,284.88/661.15
  6. Step 6: Final answer
    x = 298.40

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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.