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Finding the Fourth Proportional to 1,125.50, 1,689.12 and 781.25

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Solution

The fourth proportional to 1,125.50, 1,689.12 and 781.25 is: 1,172.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,125.50 : 1,689.12 = 781.25 : x
  2. Step 2: Convert to fraction form
    1,125.50/1,689.12 = 781.25/x
  3. Step 3: Cross multiply
    1,125.50x = 1,689.12 × 781.25
  4. Step 4: Simplify right side
    1,125.50x = 1,319,625
  5. Step 5: Solve for x
    x = 1,319,625/1,125.50
  6. Step 6: Final answer
    x = 1,172.48

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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.