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Finding the Fourth Proportional to 213.60, 320.40 and 91.79

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Solution

The fourth proportional to 213.60, 320.40 and 91.79 is: 137.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.60 : 320.40 = 91.79 : x
  2. Step 2: Convert to fraction form
    213.60/320.40 = 91.79/x
  3. Step 3: Cross multiply
    213.60x = 320.40 × 91.79
  4. Step 4: Simplify right side
    213.60x = 29,409.12
  5. Step 5: Solve for x
    x = 29,409.12/213.60
  6. Step 6: Final answer
    x = 137.68

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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.