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Finding the Fourth Proportional to 206.25, 309.38 and 78

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Solution

The fourth proportional to 206.25, 309.38 and 78 is: 117

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.25 : 309.38 = 78 : x
  2. Step 2: Convert to fraction form
    206.25/309.38 = 78/x
  3. Step 3: Cross multiply
    206.25x = 309.38 × 78
  4. Step 4: Simplify right side
    206.25x = 24,131.25
  5. Step 5: Solve for x
    x = 24,131.25/206.25
  6. Step 6: Final answer
    x = 117

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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.