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Finding the Fourth Proportional to 77.88, 107.40 and 65.76

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Solution

The fourth proportional to 77.88, 107.40 and 65.76 is: 90.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.88 : 107.40 = 65.76 : x
  2. Step 2: Convert to fraction form
    77.88/107.40 = 65.76/x
  3. Step 3: Cross multiply
    77.88x = 107.40 × 65.76
  4. Step 4: Simplify right side
    77.88x = 7,062.62
  5. Step 5: Solve for x
    x = 7,062.62/77.88
  6. Step 6: Final answer
    x = 90.69

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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.