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Finding the Fourth Proportional to 87.70, 121.02 and 78.46

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Solution

The fourth proportional to 87.70, 121.02 and 78.46 is: 108.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.70 : 121.02 = 78.46 : x
  2. Step 2: Convert to fraction form
    87.70/121.02 = 78.46/x
  3. Step 3: Cross multiply
    87.70x = 121.02 × 78.46
  4. Step 4: Simplify right side
    87.70x = 9,495.23
  5. Step 5: Solve for x
    x = 9,495.23/87.70
  6. Step 6: Final answer
    x = 108.27

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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.