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Finding the Fourth Proportional to 87.92, 121.56 and 64.88

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Solution

The fourth proportional to 87.92, 121.56 and 64.88 is: 89.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.92 : 121.56 = 64.88 : x
  2. Step 2: Convert to fraction form
    87.92/121.56 = 64.88/x
  3. Step 3: Cross multiply
    87.92x = 121.56 × 64.88
  4. Step 4: Simplify right side
    87.92x = 7,886.81
  5. Step 5: Solve for x
    x = 7,886.81/87.92
  6. Step 6: Final answer
    x = 89.70

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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.