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Finding the Fourth Proportional to 78.60, 108.51 and 66.39

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Solution

The fourth proportional to 78.60, 108.51 and 66.39 is: 91.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.60 : 108.51 = 66.39 : x
  2. Step 2: Convert to fraction form
    78.60/108.51 = 66.39/x
  3. Step 3: Cross multiply
    78.60x = 108.51 × 66.39
  4. Step 4: Simplify right side
    78.60x = 7,203.98
  5. Step 5: Solve for x
    x = 7,203.98/78.60
  6. Step 6: Final answer
    x = 91.65

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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.