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Finding the Fourth Proportional to 145.31, 217.79 and 76.81

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Solution

The fourth proportional to 145.31, 217.79 and 76.81 is: 115.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    145.31 : 217.79 = 76.81 : x
  2. Step 2: Convert to fraction form
    145.31/217.79 = 76.81/x
  3. Step 3: Cross multiply
    145.31x = 217.79 × 76.81
  4. Step 4: Simplify right side
    145.31x = 16,728.52
  5. Step 5: Solve for x
    x = 16,728.52/145.31
  6. Step 6: Final answer
    x = 115.13

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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.