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Finding the Fourth Proportional to 87.78, 121.14 and 66

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Solution

The fourth proportional to 87.78, 121.14 and 66 is: 91.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.78 : 121.14 = 66 : x
  2. Step 2: Convert to fraction form
    87.78/121.14 = 66/x
  3. Step 3: Cross multiply
    87.78x = 121.14 × 66
  4. Step 4: Simplify right side
    87.78x = 7,995.24
  5. Step 5: Solve for x
    x = 7,995.24/87.78
  6. Step 6: Final answer
    x = 91.08

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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.