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Finding the Fourth Proportional to 1,987.84, 2,981.35 and 688.87

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Solution

The fourth proportional to 1,987.84, 2,981.35 and 688.87 is: 1,033.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.84 : 2,981.35 = 688.87 : x
  2. Step 2: Convert to fraction form
    1,987.84/2,981.35 = 688.87/x
  3. Step 3: Cross multiply
    1,987.84x = 2,981.35 × 688.87
  4. Step 4: Simplify right side
    1,987.84x = 2,053,762.57
  5. Step 5: Solve for x
    x = 2,053,762.57/1,987.84
  6. Step 6: Final answer
    x = 1,033.16

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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.