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Finding the Fourth Proportional to 213.53, 320.40 and 91.78

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Solution

The fourth proportional to 213.53, 320.40 and 91.78 is: 137.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.53 : 320.40 = 91.78 : x
  2. Step 2: Convert to fraction form
    213.53/320.40 = 91.78/x
  3. Step 3: Cross multiply
    213.53x = 320.40 × 91.78
  4. Step 4: Simplify right side
    213.53x = 29,405.51
  5. Step 5: Solve for x
    x = 29,405.51/213.53
  6. Step 6: Final answer
    x = 137.71

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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.