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Finding the Fourth Proportional to 998.80, 1,379.80 and 790.36

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Solution

The fourth proportional to 998.80, 1,379.80 and 790.36 is: 1,091.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    998.80 : 1,379.80 = 790.36 : x
  2. Step 2: Convert to fraction form
    998.80/1,379.80 = 790.36/x
  3. Step 3: Cross multiply
    998.80x = 1,379.80 × 790.36
  4. Step 4: Simplify right side
    998.80x = 1,090,538.73
  5. Step 5: Solve for x
    x = 1,090,538.73/998.80
  6. Step 6: Final answer
    x = 1,091.85

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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.