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Finding the Fourth Proportional to 1,679.80, 2,517.90 and 639.40

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Solution

The fourth proportional to 1,679.80, 2,517.90 and 639.40 is: 958.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,679.80 : 2,517.90 = 639.40 : x
  2. Step 2: Convert to fraction form
    1,679.80/2,517.90 = 639.40/x
  3. Step 3: Cross multiply
    1,679.80x = 2,517.90 × 639.40
  4. Step 4: Simplify right side
    1,679.80x = 1,609,945.26
  5. Step 5: Solve for x
    x = 1,609,945.26/1,679.80
  6. Step 6: Final answer
    x = 958.41

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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.