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Finding the Fourth Proportional to 153.15, 211.65 and 128.54

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Solution

The fourth proportional to 153.15, 211.65 and 128.54 is: 177.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    153.15 : 211.65 = 128.54 : x
  2. Step 2: Convert to fraction form
    153.15/211.65 = 128.54/x
  3. Step 3: Cross multiply
    153.15x = 211.65 × 128.54
  4. Step 4: Simplify right side
    153.15x = 27,205.49
  5. Step 5: Solve for x
    x = 27,205.49/153.15
  6. Step 6: Final answer
    x = 177.64

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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.