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Finding the Fourth Proportional to 1,387.58, 2,081.67 and 521.90

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Solution

The fourth proportional to 1,387.58, 2,081.67 and 521.90 is: 782.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.58 : 2,081.67 = 521.90 : x
  2. Step 2: Convert to fraction form
    1,387.58/2,081.67 = 521.90/x
  3. Step 3: Cross multiply
    1,387.58x = 2,081.67 × 521.90
  4. Step 4: Simplify right side
    1,387.58x = 1,086,413.16
  5. Step 5: Solve for x
    x = 1,086,413.16/1,387.58
  6. Step 6: Final answer
    x = 782.96

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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.