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Finding the Fourth Proportional to 101.40, 139.92 and 57.15

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Solution

The fourth proportional to 101.40, 139.92 and 57.15 is: 78.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    101.40 : 139.92 = 57.15 : x
  2. Step 2: Convert to fraction form
    101.40/139.92 = 57.15/x
  3. Step 3: Cross multiply
    101.40x = 139.92 × 57.15
  4. Step 4: Simplify right side
    101.40x = 7,996.43
  5. Step 5: Solve for x
    x = 7,996.43/101.40
  6. Step 6: Final answer
    x = 78.86

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.