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Finding the Fourth Proportional to 42.92, 64.40 and 15.87

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Solution

The fourth proportional to 42.92, 64.40 and 15.87 is: 23.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.92 : 64.40 = 15.87 : x
  2. Step 2: Convert to fraction form
    42.92/64.40 = 15.87/x
  3. Step 3: Cross multiply
    42.92x = 64.40 × 15.87
  4. Step 4: Simplify right side
    42.92x = 1,021.95
  5. Step 5: Solve for x
    x = 1,021.95/42.92
  6. Step 6: Final answer
    x = 23.81

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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.