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Finding the Fourth Proportional to 2,721.78, 4,081.86 and 990

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Solution

The fourth proportional to 2,721.78, 4,081.86 and 990 is: 1,484.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,721.78 : 4,081.86 = 990 : x
  2. Step 2: Convert to fraction form
    2,721.78/4,081.86 = 990/x
  3. Step 3: Cross multiply
    2,721.78x = 4,081.86 × 990
  4. Step 4: Simplify right side
    2,721.78x = 4,041,041.40
  5. Step 5: Solve for x
    x = 4,041,041.40/2,721.78
  6. Step 6: Final answer
    x = 1,484.71

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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.