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Finding the Fourth Proportional to 19,785.70, 29,680.90 and 12,390.78

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Solution

The fourth proportional to 19,785.70, 29,680.90 and 12,390.78 is: 18,587.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    19,785.70 : 29,680.90 = 12,390.78 : x
  2. Step 2: Convert to fraction form
    19,785.70/29,680.90 = 12,390.78/x
  3. Step 3: Cross multiply
    19,785.70x = 29,680.90 × 12,390.78
  4. Step 4: Simplify right side
    19,785.70x = 367,769,291.74
  5. Step 5: Solve for x
    x = 367,769,291.74/19,785.70
  6. Step 6: Final answer
    x = 18,587.63

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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.