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Finding the Fourth Proportional to 78.45, 107.73 and 66.15

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Solution

The fourth proportional to 78.45, 107.73 and 66.15 is: 90.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.45 : 107.73 = 66.15 : x
  2. Step 2: Convert to fraction form
    78.45/107.73 = 66.15/x
  3. Step 3: Cross multiply
    78.45x = 107.73 × 66.15
  4. Step 4: Simplify right side
    78.45x = 7,126.50
  5. Step 5: Solve for x
    x = 7,126.50/78.45
  6. Step 6: Final answer
    x = 90.84

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.