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Finding the Fourth Proportional to 66.15, 99.12 and 31.87

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Solution

The fourth proportional to 66.15, 99.12 and 31.87 is: 47.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.15 : 99.12 = 31.87 : x
  2. Step 2: Convert to fraction form
    66.15/99.12 = 31.87/x
  3. Step 3: Cross multiply
    66.15x = 99.12 × 31.87
  4. Step 4: Simplify right side
    66.15x = 3,158.95
  5. Step 5: Solve for x
    x = 3,158.95/66.15
  6. Step 6: Final answer
    x = 47.75

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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.