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Finding the Fourth Proportional to 76.64, 105.20 and 72.56

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Solution

The fourth proportional to 76.64, 105.20 and 72.56 is: 99.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.64 : 105.20 = 72.56 : x
  2. Step 2: Convert to fraction form
    76.64/105.20 = 72.56/x
  3. Step 3: Cross multiply
    76.64x = 105.20 × 72.56
  4. Step 4: Simplify right side
    76.64x = 7,633.31
  5. Step 5: Solve for x
    x = 7,633.31/76.64
  6. Step 6: Final answer
    x = 99.60

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.