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Finding the Fourth Proportional to 82.85, 123.55 and 78.90

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Solution

The fourth proportional to 82.85, 123.55 and 78.90 is: 117.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.85 : 123.55 = 78.90 : x
  2. Step 2: Convert to fraction form
    82.85/123.55 = 78.90/x
  3. Step 3: Cross multiply
    82.85x = 123.55 × 78.90
  4. Step 4: Simplify right side
    82.85x = 9,748.00
  5. Step 5: Solve for x
    x = 9,748.00/82.85
  6. Step 6: Final answer
    x = 117.66

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.