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Finding the Fourth Proportional to 312.96, 431.68 and 208.20

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Solution

The fourth proportional to 312.96, 431.68 and 208.20 is: 287.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.96 : 431.68 = 208.20 : x
  2. Step 2: Convert to fraction form
    312.96/431.68 = 208.20/x
  3. Step 3: Cross multiply
    312.96x = 431.68 × 208.20
  4. Step 4: Simplify right side
    312.96x = 89,875.78
  5. Step 5: Solve for x
    x = 89,875.78/312.96
  6. Step 6: Final answer
    x = 287.18

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.