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Finding the Fourth Proportional to 66.14, 91.21 and 56.91

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Solution

The fourth proportional to 66.14, 91.21 and 56.91 is: 78.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.14 : 91.21 = 56.91 : x
  2. Step 2: Convert to fraction form
    66.14/91.21 = 56.91/x
  3. Step 3: Cross multiply
    66.14x = 91.21 × 56.91
  4. Step 4: Simplify right side
    66.14x = 5,190.76
  5. Step 5: Solve for x
    x = 5,190.76/66.14
  6. Step 6: Final answer
    x = 78.48

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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.