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Finding the Fourth Proportional to 1,289.40, 1,932.48 and 639.96

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Solution

The fourth proportional to 1,289.40, 1,932.48 and 639.96 is: 959.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,289.40 : 1,932.48 = 639.96 : x
  2. Step 2: Convert to fraction form
    1,289.40/1,932.48 = 639.96/x
  3. Step 3: Cross multiply
    1,289.40x = 1,932.48 × 639.96
  4. Step 4: Simplify right side
    1,289.40x = 1,236,709.90
  5. Step 5: Solve for x
    x = 1,236,709.90/1,289.40
  6. Step 6: Final answer
    x = 959.14

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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.