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Finding the Fourth Proportional to 209.31, 313.96 and 87.40

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Solution

The fourth proportional to 209.31, 313.96 and 87.40 is: 131.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.31 : 313.96 = 87.40 : x
  2. Step 2: Convert to fraction form
    209.31/313.96 = 87.40/x
  3. Step 3: Cross multiply
    209.31x = 313.96 × 87.40
  4. Step 4: Simplify right side
    209.31x = 27,440.10
  5. Step 5: Solve for x
    x = 27,440.10/209.31
  6. Step 6: Final answer
    x = 131.10

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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.