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Finding the Fourth Proportional to 42.76, 64.15 and 13.87

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Solution

The fourth proportional to 42.76, 64.15 and 13.87 is: 20.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.76 : 64.15 = 13.87 : x
  2. Step 2: Convert to fraction form
    42.76/64.15 = 13.87/x
  3. Step 3: Cross multiply
    42.76x = 64.15 × 13.87
  4. Step 4: Simplify right side
    42.76x = 889.42
  5. Step 5: Solve for x
    x = 889.42/42.76
  6. Step 6: Final answer
    x = 20.80

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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.