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Finding the Fourth Proportional to 20,820.80, 31,231.20 and 12,078.20

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Solution

The fourth proportional to 20,820.80, 31,231.20 and 12,078.20 is: 18,117.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    20,820.80 : 31,231.20 = 12,078.20 : x
  2. Step 2: Convert to fraction form
    20,820.80/31,231.20 = 12,078.20/x
  3. Step 3: Cross multiply
    20,820.80x = 31,231.20 × 12,078.20
  4. Step 4: Simplify right side
    20,820.80x = 377,216,679.84
  5. Step 5: Solve for x
    x = 377,216,679.84/20,820.80
  6. Step 6: Final answer
    x = 18,117.30

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1.5x scale

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.