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Finding the Fourth Proportional to 1,987.77, 2,981.79 and 689.34

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Solution

The fourth proportional to 1,987.77, 2,981.79 and 689.34 is: 1,034.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.77 : 2,981.79 = 689.34 : x
  2. Step 2: Convert to fraction form
    1,987.77/2,981.79 = 689.34/x
  3. Step 3: Cross multiply
    1,987.77x = 2,981.79 × 689.34
  4. Step 4: Simplify right side
    1,987.77x = 2,055,467.12
  5. Step 5: Solve for x
    x = 2,055,467.12/1,987.77
  6. Step 6: Final answer
    x = 1,034.06

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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.