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Finding the Fourth Proportional to 1,125.10, 1,687.65 and 639.10

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Solution

The fourth proportional to 1,125.10, 1,687.65 and 639.10 is: 958.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,125.10 : 1,687.65 = 639.10 : x
  2. Step 2: Convert to fraction form
    1,125.10/1,687.65 = 639.10/x
  3. Step 3: Cross multiply
    1,125.10x = 1,687.65 × 639.10
  4. Step 4: Simplify right side
    1,125.10x = 1,078,577.12
  5. Step 5: Solve for x
    x = 1,078,577.12/1,125.10
  6. Step 6: Final answer
    x = 958.65

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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.