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Finding the Fourth Proportional to 123.97, 186 and 78.31

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Solution

The fourth proportional to 123.97, 186 and 78.31 is: 117.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.97 : 186 = 78.31 : x
  2. Step 2: Convert to fraction form
    123.97/186 = 78.31/x
  3. Step 3: Cross multiply
    123.97x = 186 × 78.31
  4. Step 4: Simplify right side
    123.97x = 14,565.66
  5. Step 5: Solve for x
    x = 14,565.66/123.97
  6. Step 6: Final answer
    x = 117.49

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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.