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Finding the Fourth Proportional to 91.20, 125.76 and 72.64

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Solution

The fourth proportional to 91.20, 125.76 and 72.64 is: 100.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.20 : 125.76 = 72.64 : x
  2. Step 2: Convert to fraction form
    91.20/125.76 = 72.64/x
  3. Step 3: Cross multiply
    91.20x = 125.76 × 72.64
  4. Step 4: Simplify right side
    91.20x = 9,135.21
  5. Step 5: Solve for x
    x = 9,135.21/91.20
  6. Step 6: Final answer
    x = 100.17

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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.