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Finding the Fourth Proportional to 212.80, 319.20 and 209.60

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Solution

The fourth proportional to 212.80, 319.20 and 209.60 is: 314.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.80 : 319.20 = 209.60 : x
  2. Step 2: Convert to fraction form
    212.80/319.20 = 209.60/x
  3. Step 3: Cross multiply
    212.80x = 319.20 × 209.60
  4. Step 4: Simplify right side
    212.80x = 66,904.32
  5. Step 5: Solve for x
    x = 66,904.32/212.80
  6. Step 6: Final answer
    x = 314.40

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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.