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Finding the Fourth Proportional to 1,987.40, 2,981.22 and 688.70

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Solution

The fourth proportional to 1,987.40, 2,981.22 and 688.70 is: 1,033.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.40 : 2,981.22 = 688.70 : x
  2. Step 2: Convert to fraction form
    1,987.40/2,981.22 = 688.70/x
  3. Step 3: Cross multiply
    1,987.40x = 2,981.22 × 688.70
  4. Step 4: Simplify right side
    1,987.40x = 2,053,166.21
  5. Step 5: Solve for x
    x = 2,053,166.21/1,987.40
  6. Step 6: Final answer
    x = 1,033.09

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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.