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Finding the Fourth Proportional to 209.88, 314.64 and 84.78

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Solution

The fourth proportional to 209.88, 314.64 and 84.78 is: 127.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.88 : 314.64 = 84.78 : x
  2. Step 2: Convert to fraction form
    209.88/314.64 = 84.78/x
  3. Step 3: Cross multiply
    209.88x = 314.64 × 84.78
  4. Step 4: Simplify right side
    209.88x = 26,675.18
  5. Step 5: Solve for x
    x = 26,675.18/209.88
  6. Step 6: Final answer
    x = 127.10

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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.