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Finding the Fourth Proportional to 81, 121.47 and 28.22

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Solution

The fourth proportional to 81, 121.47 and 28.22 is: 42.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    81 : 121.47 = 28.22 : x
  2. Step 2: Convert to fraction form
    81/121.47 = 28.22/x
  3. Step 3: Cross multiply
    81x = 121.47 × 28.22
  4. Step 4: Simplify right side
    81x = 3,428.19
  5. Step 5: Solve for x
    x = 3,428.19/81
  6. Step 6: Final answer
    x = 42.32

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.