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Finding the Fourth Proportional to 81, 121.51 and 71.95

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Solution

The fourth proportional to 81, 121.51 and 71.95 is: 107.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    81 : 121.51 = 71.95 : x
  2. Step 2: Convert to fraction form
    81/121.51 = 71.95/x
  3. Step 3: Cross multiply
    81x = 121.51 × 71.95
  4. Step 4: Simplify right side
    81x = 8,742.16
  5. Step 5: Solve for x
    x = 8,742.16/81
  6. Step 6: Final answer
    x = 107.93

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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.