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Finding the Fourth Proportional to 71.87, 99.18 and 39.12

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Solution

The fourth proportional to 71.87, 99.18 and 39.12 is: 53.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.87 : 99.18 = 39.12 : x
  2. Step 2: Convert to fraction form
    71.87/99.18 = 39.12/x
  3. Step 3: Cross multiply
    71.87x = 99.18 × 39.12
  4. Step 4: Simplify right side
    71.87x = 3,880.34
  5. Step 5: Solve for x
    x = 3,880.34/71.87
  6. Step 6: Final answer
    x = 53.99

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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.