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Finding the Fourth Proportional to 82.72, 123.32 and 78.40

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Solution

The fourth proportional to 82.72, 123.32 and 78.40 is: 116.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.72 : 123.32 = 78.40 : x
  2. Step 2: Convert to fraction form
    82.72/123.32 = 78.40/x
  3. Step 3: Cross multiply
    82.72x = 123.32 × 78.40
  4. Step 4: Simplify right side
    82.72x = 9,668.29
  5. Step 5: Solve for x
    x = 9,668.29/82.72
  6. Step 6: Final answer
    x = 116.88

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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.