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Finding the Fourth Proportional to 100.56, 138.78 and 66

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Solution

The fourth proportional to 100.56, 138.78 and 66 is: 91.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.56 : 138.78 = 66 : x
  2. Step 2: Convert to fraction form
    100.56/138.78 = 66/x
  3. Step 3: Cross multiply
    100.56x = 138.78 × 66
  4. Step 4: Simplify right side
    100.56x = 9,159.48
  5. Step 5: Solve for x
    x = 9,159.48/100.56
  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.