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Finding the Fourth Proportional to 690.61, 1,037.96 and 639.68

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Solution

The fourth proportional to 690.61, 1,037.96 and 639.68 is: 961.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.61 : 1,037.96 = 639.68 : x
  2. Step 2: Convert to fraction form
    690.61/1,037.96 = 639.68/x
  3. Step 3: Cross multiply
    690.61x = 1,037.96 × 639.68
  4. Step 4: Simplify right side
    690.61x = 663,959.05
  5. Step 5: Solve for x
    x = 663,959.05/690.61
  6. Step 6: Final answer
    x = 961.42

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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.