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Finding the Fourth Proportional to 77.60, 106.90 and 65.31

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Solution

The fourth proportional to 77.60, 106.90 and 65.31 is: 89.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.60 : 106.90 = 65.31 : x
  2. Step 2: Convert to fraction form
    77.60/106.90 = 65.31/x
  3. Step 3: Cross multiply
    77.60x = 106.90 × 65.31
  4. Step 4: Simplify right side
    77.60x = 6,981.64
  5. Step 5: Solve for x
    x = 6,981.64/77.60
  6. Step 6: Final answer
    x = 89.97

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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.