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Finding the Fourth Proportional to 13,985.60, 20,978.40 and 12,859.20

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Solution

The fourth proportional to 13,985.60, 20,978.40 and 12,859.20 is: 19,288.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    13,985.60 : 20,978.40 = 12,859.20 : x
  2. Step 2: Convert to fraction form
    13,985.60/20,978.40 = 12,859.20/x
  3. Step 3: Cross multiply
    13,985.60x = 20,978.40 × 12,859.20
  4. Step 4: Simplify right side
    13,985.60x = 269,765,441.28
  5. Step 5: Solve for x
    x = 269,765,441.28/13,985.60
  6. Step 6: Final answer
    x = 19,288.80

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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.