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Finding the Fourth Proportional to 66.78, 91.31 and 64.26

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Solution

The fourth proportional to 66.78, 91.31 and 64.26 is: 87.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.78 : 91.31 = 64.26 : x
  2. Step 2: Convert to fraction form
    66.78/91.31 = 64.26/x
  3. Step 3: Cross multiply
    66.78x = 91.31 × 64.26
  4. Step 4: Simplify right side
    66.78x = 5,867.26
  5. Step 5: Solve for x
    x = 5,867.26/66.78
  6. Step 6: Final answer
    x = 87.86

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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.