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Finding the Fourth Proportional to 82.40, 123.60 and 77.12

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Solution

The fourth proportional to 82.40, 123.60 and 77.12 is: 115.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.40 : 123.60 = 77.12 : x
  2. Step 2: Convert to fraction form
    82.40/123.60 = 77.12/x
  3. Step 3: Cross multiply
    82.40x = 123.60 × 77.12
  4. Step 4: Simplify right side
    82.40x = 9,532.03
  5. Step 5: Solve for x
    x = 9,532.03/82.40
  6. Step 6: Final answer
    x = 115.68

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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.