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Finding the Fourth Proportional to 1,128.49, 1,690.57 and 688.43

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Solution

The fourth proportional to 1,128.49, 1,690.57 and 688.43 is: 1,031.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,128.49 : 1,690.57 = 688.43 : x
  2. Step 2: Convert to fraction form
    1,128.49/1,690.57 = 688.43/x
  3. Step 3: Cross multiply
    1,128.49x = 1,690.57 × 688.43
  4. Step 4: Simplify right side
    1,128.49x = 1,163,841.61
  5. Step 5: Solve for x
    x = 1,163,841.61/1,128.49
  6. Step 6: Final answer
    x = 1,031.33

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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.