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Finding the Fourth Proportional to 83.40, 115.20 and 65.21

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Solution

The fourth proportional to 83.40, 115.20 and 65.21 is: 90.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    83.40 : 115.20 = 65.21 : x
  2. Step 2: Convert to fraction form
    83.40/115.20 = 65.21/x
  3. Step 3: Cross multiply
    83.40x = 115.20 × 65.21
  4. Step 4: Simplify right side
    83.40x = 7,511.62
  5. Step 5: Solve for x
    x = 7,511.62/83.40
  6. Step 6: Final answer
    x = 90.07

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.