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Finding the Fourth Proportional to 1,288.72, 1,932 and 638.56

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Solution

The fourth proportional to 1,288.72, 1,932 and 638.56 is: 957.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,288.72 : 1,932 = 638.56 : x
  2. Step 2: Convert to fraction form
    1,288.72/1,932 = 638.56/x
  3. Step 3: Cross multiply
    1,288.72x = 1,932 × 638.56
  4. Step 4: Simplify right side
    1,288.72x = 1,233,697.92
  5. Step 5: Solve for x
    x = 1,233,697.92/1,288.72
  6. Step 6: Final answer
    x = 957.30

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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.