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Finding the Fourth Proportional to 1,987.07, 2,981.81 and 689.45

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Solution

The fourth proportional to 1,987.07, 2,981.81 and 689.45 is: 1,034.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.07 : 2,981.81 = 689.45 : x
  2. Step 2: Convert to fraction form
    1,987.07/2,981.81 = 689.45/x
  3. Step 3: Cross multiply
    1,987.07x = 2,981.81 × 689.45
  4. Step 4: Simplify right side
    1,987.07x = 2,055,805.46
  5. Step 5: Solve for x
    x = 2,055,805.46/1,987.07
  6. Step 6: Final answer
    x = 1,034.59

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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.