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Finding the Fourth Proportional to 66.55, 99.78 and 20.88

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Solution

The fourth proportional to 66.55, 99.78 and 20.88 is: 31.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.55 : 99.78 = 20.88 : x
  2. Step 2: Convert to fraction form
    66.55/99.78 = 20.88/x
  3. Step 3: Cross multiply
    66.55x = 99.78 × 20.88
  4. Step 4: Simplify right side
    66.55x = 2,083.41
  5. Step 5: Solve for x
    x = 2,083.41/66.55
  6. Step 6: Final answer
    x = 31.31

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.