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Finding the Fourth Proportional to 72.88, 108.64 and 72.40

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Solution

The fourth proportional to 72.88, 108.64 and 72.40 is: 107.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.88 : 108.64 = 72.40 : x
  2. Step 2: Convert to fraction form
    72.88/108.64 = 72.40/x
  3. Step 3: Cross multiply
    72.88x = 108.64 × 72.40
  4. Step 4: Simplify right side
    72.88x = 7,865.54
  5. Step 5: Solve for x
    x = 7,865.54/72.88
  6. Step 6: Final answer
    x = 107.92

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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.