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Finding the Fourth Proportional to 998.88, 1,379.08 and 645.40

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Solution

The fourth proportional to 998.88, 1,379.08 and 645.40 is: 891.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    998.88 : 1,379.08 = 645.40 : x
  2. Step 2: Convert to fraction form
    998.88/1,379.08 = 645.40/x
  3. Step 3: Cross multiply
    998.88x = 1,379.08 × 645.40
  4. Step 4: Simplify right side
    998.88x = 890,058.23
  5. Step 5: Solve for x
    x = 890,058.23/998.88
  6. Step 6: Final answer
    x = 891.06

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.