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Finding the Fourth Proportional to 211.10, 291.20 and 128.24

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Solution

The fourth proportional to 211.10, 291.20 and 128.24 is: 176.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.10 : 291.20 = 128.24 : x
  2. Step 2: Convert to fraction form
    211.10/291.20 = 128.24/x
  3. Step 3: Cross multiply
    211.10x = 291.20 × 128.24
  4. Step 4: Simplify right side
    211.10x = 37,343.49
  5. Step 5: Solve for x
    x = 37,343.49/211.10
  6. Step 6: Final answer
    x = 176.90

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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.