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Finding the Fourth Proportional to 82.89, 123.75 and 78.21

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Solution

The fourth proportional to 82.89, 123.75 and 78.21 is: 116.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.89 : 123.75 = 78.21 : x
  2. Step 2: Convert to fraction form
    82.89/123.75 = 78.21/x
  3. Step 3: Cross multiply
    82.89x = 123.75 × 78.21
  4. Step 4: Simplify right side
    82.89x = 9,678.49
  5. Step 5: Solve for x
    x = 9,678.49/82.89
  6. Step 6: Final answer
    x = 116.76

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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.