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Finding the Fourth Proportional to 42.81, 63.99 and 31.87

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Solution

The fourth proportional to 42.81, 63.99 and 31.87 is: 47.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.81 : 63.99 = 31.87 : x
  2. Step 2: Convert to fraction form
    42.81/63.99 = 31.87/x
  3. Step 3: Cross multiply
    42.81x = 63.99 × 31.87
  4. Step 4: Simplify right side
    42.81x = 2,039.38
  5. Step 5: Solve for x
    x = 2,039.38/42.81
  6. Step 6: Final answer
    x = 47.64

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.