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Finding the Fourth Proportional to 72, 107.28 and 68.40

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Solution

The fourth proportional to 72, 107.28 and 68.40 is: 101.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    72 : 107.28 = 68.40 : x
  2. Step 2: Convert to fraction form
    72/107.28 = 68.40/x
  3. Step 3: Cross multiply
    72x = 107.28 × 68.40
  4. Step 4: Simplify right side
    72x = 7,337.95
  5. Step 5: Solve for x
    x = 7,337.95/72
  6. Step 6: Final answer
    x = 101.92

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.