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Finding the Fourth Proportional to 213.18, 319.80 and 91.45

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Solution

The fourth proportional to 213.18, 319.80 and 91.45 is: 137.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.18 : 319.80 = 91.45 : x
  2. Step 2: Convert to fraction form
    213.18/319.80 = 91.45/x
  3. Step 3: Cross multiply
    213.18x = 319.80 × 91.45
  4. Step 4: Simplify right side
    213.18x = 29,244.11
  5. Step 5: Solve for x
    x = 29,244.11/213.18
  6. Step 6: Final answer
    x = 137.18

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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.