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Finding the Fourth Proportional to 1,689.12, 2,531.25 and 811.35

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Solution

The fourth proportional to 1,689.12, 2,531.25 and 811.35 is: 1,215.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,689.12 : 2,531.25 = 811.35 : x
  2. Step 2: Convert to fraction form
    1,689.12/2,531.25 = 811.35/x
  3. Step 3: Cross multiply
    1,689.12x = 2,531.25 × 811.35
  4. Step 4: Simplify right side
    1,689.12x = 2,053,729.69
  5. Step 5: Solve for x
    x = 2,053,729.69/1,689.12
  6. Step 6: Final answer
    x = 1,215.86

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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.