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Finding the Fourth Proportional to 213.02, 319.40 and 91.21

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Solution

The fourth proportional to 213.02, 319.40 and 91.21 is: 136.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.02 : 319.40 = 91.21 : x
  2. Step 2: Convert to fraction form
    213.02/319.40 = 91.21/x
  3. Step 3: Cross multiply
    213.02x = 319.40 × 91.21
  4. Step 4: Simplify right side
    213.02x = 29,132.47
  5. Step 5: Solve for x
    x = 29,132.47/213.02
  6. Step 6: Final answer
    x = 136.76

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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.