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Finding the Fourth Proportional to 208.60, 312.90 and 105.90

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Solution

The fourth proportional to 208.60, 312.90 and 105.90 is: 158.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.60 : 312.90 = 105.90 : x
  2. Step 2: Convert to fraction form
    208.60/312.90 = 105.90/x
  3. Step 3: Cross multiply
    208.60x = 312.90 × 105.90
  4. Step 4: Simplify right side
    208.60x = 33,136.11
  5. Step 5: Solve for x
    x = 33,136.11/208.60
  6. Step 6: Final answer
    x = 158.85

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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.