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Finding the Fourth Proportional to 259.10, 388.64 and 85.76

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Solution

The fourth proportional to 259.10, 388.64 and 85.76 is: 128.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.10 : 388.64 = 85.76 : x
  2. Step 2: Convert to fraction form
    259.10/388.64 = 85.76/x
  3. Step 3: Cross multiply
    259.10x = 388.64 × 85.76
  4. Step 4: Simplify right side
    259.10x = 33,329.77
  5. Step 5: Solve for x
    x = 33,329.77/259.10
  6. Step 6: Final answer
    x = 128.64

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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.