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Finding the Fourth Proportional to 259.40, 389.16 and 76.80

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Solution

The fourth proportional to 259.40, 389.16 and 76.80 is: 115.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.40 : 389.16 = 76.80 : x
  2. Step 2: Convert to fraction form
    259.40/389.16 = 76.80/x
  3. Step 3: Cross multiply
    259.40x = 389.16 × 76.80
  4. Step 4: Simplify right side
    259.40x = 29,887.49
  5. Step 5: Solve for x
    x = 29,887.49/259.40
  6. Step 6: Final answer
    x = 115.22

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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.