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Finding the Fourth Proportional to 1,288.78, 1,933.88 and 639.56

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Solution

The fourth proportional to 1,288.78, 1,933.88 and 639.56 is: 959.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,288.78 : 1,933.88 = 639.56 : x
  2. Step 2: Convert to fraction form
    1,288.78/1,933.88 = 639.56/x
  3. Step 3: Cross multiply
    1,288.78x = 1,933.88 × 639.56
  4. Step 4: Simplify right side
    1,288.78x = 1,236,833.93
  5. Step 5: Solve for x
    x = 1,236,833.93/1,288.78
  6. Step 6: Final answer
    x = 959.70

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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.