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Finding the Fourth Proportional to 213.15, 319.80 and 91.42

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Solution

The fourth proportional to 213.15, 319.80 and 91.42 is: 137.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.15 : 319.80 = 91.42 : x
  2. Step 2: Convert to fraction form
    213.15/319.80 = 91.42/x
  3. Step 3: Cross multiply
    213.15x = 319.80 × 91.42
  4. Step 4: Simplify right side
    213.15x = 29,236.12
  5. Step 5: Solve for x
    x = 29,236.12/213.15
  6. Step 6: Final answer
    x = 137.16

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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.