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Finding the Fourth Proportional to 12,905.40, 17,809.20 and 8,420.64

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Solution

The fourth proportional to 12,905.40, 17,809.20 and 8,420.64 is: 11,620.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    12,905.40 : 17,809.20 = 8,420.64 : x
  2. Step 2: Convert to fraction form
    12,905.40/17,809.20 = 8,420.64/x
  3. Step 3: Cross multiply
    12,905.40x = 17,809.20 × 8,420.64
  4. Step 4: Simplify right side
    12,905.40x = 149,964,861.89
  5. Step 5: Solve for x
    x = 149,964,861.89/12,905.40
  6. Step 6: Final answer
    x = 11,620.32

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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.