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Finding the Fourth Proportional to 211.20, 291.48 and 128.32

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Solution

The fourth proportional to 211.20, 291.48 and 128.32 is: 177.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.20 : 291.48 = 128.32 : x
  2. Step 2: Convert to fraction form
    211.20/291.48 = 128.32/x
  3. Step 3: Cross multiply
    211.20x = 291.48 × 128.32
  4. Step 4: Simplify right side
    211.20x = 37,402.71
  5. Step 5: Solve for x
    x = 37,402.71/211.20
  6. Step 6: Final answer
    x = 177.10

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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.