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Finding the Fourth Proportional to 991.57, 1,487.13 and 639.11

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Solution

The fourth proportional to 991.57, 1,487.13 and 639.11 is: 958.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.57 : 1,487.13 = 639.11 : x
  2. Step 2: Convert to fraction form
    991.57/1,487.13 = 639.11/x
  3. Step 3: Cross multiply
    991.57x = 1,487.13 × 639.11
  4. Step 4: Simplify right side
    991.57x = 950,439.65
  5. Step 5: Solve for x
    x = 950,439.65/991.57
  6. Step 6: Final answer
    x = 958.52

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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.