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Finding the Fourth Proportional to 20,991.78, 28,976.25 and 13,920.54

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Solution

The fourth proportional to 20,991.78, 28,976.25 and 13,920.54 is: 19,215.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    20,991.78 : 28,976.25 = 13,920.54 : x
  2. Step 2: Convert to fraction form
    20,991.78/28,976.25 = 13,920.54/x
  3. Step 3: Cross multiply
    20,991.78x = 28,976.25 × 13,920.54
  4. Step 4: Simplify right side
    20,991.78x = 403,365,047.18
  5. Step 5: Solve for x
    x = 403,365,047.18/20,991.78
  6. Step 6: Final answer
    x = 19,215.38

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1.5x scale

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.