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Finding the Fourth Proportional to 1,288.98, 1,934.09 and 639.57

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Solution

The fourth proportional to 1,288.98, 1,934.09 and 639.57 is: 959.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,288.98 : 1,934.09 = 639.57 : x
  2. Step 2: Convert to fraction form
    1,288.98/1,934.09 = 639.57/x
  3. Step 3: Cross multiply
    1,288.98x = 1,934.09 × 639.57
  4. Step 4: Simplify right side
    1,288.98x = 1,236,985.94
  5. Step 5: Solve for x
    x = 1,236,985.94/1,288.98
  6. Step 6: Final answer
    x = 959.66

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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.