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Finding the Fourth Proportional to 76.32, 105.12 and 65.92

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Solution

The fourth proportional to 76.32, 105.12 and 65.92 is: 90.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.32 : 105.12 = 65.92 : x
  2. Step 2: Convert to fraction form
    76.32/105.12 = 65.92/x
  3. Step 3: Cross multiply
    76.32x = 105.12 × 65.92
  4. Step 4: Simplify right side
    76.32x = 6,929.51
  5. Step 5: Solve for x
    x = 6,929.51/76.32
  6. Step 6: Final answer
    x = 90.80

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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.