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Finding the Fourth Proportional to 81.36, 122.64 and 74.16

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Solution

The fourth proportional to 81.36, 122.64 and 74.16 is: 111.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.36 : 122.64 = 74.16 : x
  2. Step 2: Convert to fraction form
    81.36/122.64 = 74.16/x
  3. Step 3: Cross multiply
    81.36x = 122.64 × 74.16
  4. Step 4: Simplify right side
    81.36x = 9,094.98
  5. Step 5: Solve for x
    x = 9,094.98/81.36
  6. Step 6: Final answer
    x = 111.79

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.