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Finding the Fourth Proportional to 1,987.70, 2,981.59 and 689.16

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Solution

The fourth proportional to 1,987.70, 2,981.59 and 689.16 is: 1,033.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.70 : 2,981.59 = 689.16 : x
  2. Step 2: Convert to fraction form
    1,987.70/2,981.59 = 689.16/x
  3. Step 3: Cross multiply
    1,987.70x = 2,981.59 × 689.16
  4. Step 4: Simplify right side
    1,987.70x = 2,054,790.84
  5. Step 5: Solve for x
    x = 2,054,790.84/1,987.70
  6. Step 6: Final answer
    x = 1,033.76

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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.