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Finding the Fourth Proportional to 112.87, 155.53 and 78.31

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Solution

The fourth proportional to 112.87, 155.53 and 78.31 is: 107.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    112.87 : 155.53 = 78.31 : x
  2. Step 2: Convert to fraction form
    112.87/155.53 = 78.31/x
  3. Step 3: Cross multiply
    112.87x = 155.53 × 78.31
  4. Step 4: Simplify right side
    112.87x = 12,179.55
  5. Step 5: Solve for x
    x = 12,179.55/112.87
  6. Step 6: Final answer
    x = 107.91

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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.