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Finding the Fourth Proportional to 265.61, 398.15 and 128.78

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Solution

The fourth proportional to 265.61, 398.15 and 128.78 is: 193.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    265.61 : 398.15 = 128.78 : x
  2. Step 2: Convert to fraction form
    265.61/398.15 = 128.78/x
  3. Step 3: Cross multiply
    265.61x = 398.15 × 128.78
  4. Step 4: Simplify right side
    265.61x = 51,271.12
  5. Step 5: Solve for x
    x = 51,271.12/265.61
  6. Step 6: Final answer
    x = 193.04

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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.