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Finding the Fourth Proportional to 206.51, 309.78 and 84.78

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Solution

The fourth proportional to 206.51, 309.78 and 84.78 is: 127.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    206.51 : 309.78 = 84.78 : x
  2. Step 2: Convert to fraction form
    206.51/309.78 = 84.78/x
  3. Step 3: Cross multiply
    206.51x = 309.78 × 84.78
  4. Step 4: Simplify right side
    206.51x = 26,263.15
  5. Step 5: Solve for x
    x = 26,263.15/206.51
  6. Step 6: Final answer
    x = 127.18

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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.