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Finding the Fourth Proportional to 66.80, 91.86 and 61.40

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Solution

The fourth proportional to 66.80, 91.86 and 61.40 is: 84.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.80 : 91.86 = 61.40 : x
  2. Step 2: Convert to fraction form
    66.80/91.86 = 61.40/x
  3. Step 3: Cross multiply
    66.80x = 91.86 × 61.40
  4. Step 4: Simplify right side
    66.80x = 5,640.20
  5. Step 5: Solve for x
    x = 5,640.20/66.80
  6. Step 6: Final answer
    x = 84.43

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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.