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Finding the Fourth Proportional to 213.61, 320.40 and 76.64

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Solution

The fourth proportional to 213.61, 320.40 and 76.64 is: 114.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.61 : 320.40 = 76.64 : x
  2. Step 2: Convert to fraction form
    213.61/320.40 = 76.64/x
  3. Step 3: Cross multiply
    213.61x = 320.40 × 76.64
  4. Step 4: Simplify right side
    213.61x = 24,555.46
  5. Step 5: Solve for x
    x = 24,555.46/213.61
  6. Step 6: Final answer
    x = 114.95

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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.