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Finding the Fourth Proportional to 78.32, 107.90 and 66

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Solution

The fourth proportional to 78.32, 107.90 and 66 is: 90.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.32 : 107.90 = 66 : x
  2. Step 2: Convert to fraction form
    78.32/107.90 = 66/x
  3. Step 3: Cross multiply
    78.32x = 107.90 × 66
  4. Step 4: Simplify right side
    78.32x = 7,121.40
  5. Step 5: Solve for x
    x = 7,121.40/78.32
  6. Step 6: Final answer
    x = 90.93

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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.