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Finding the Fourth Proportional to 211.20, 291.50 and 123.90

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Solution

The fourth proportional to 211.20, 291.50 and 123.90 is: 171.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.20 : 291.50 = 123.90 : x
  2. Step 2: Convert to fraction form
    211.20/291.50 = 123.90/x
  3. Step 3: Cross multiply
    211.20x = 291.50 × 123.90
  4. Step 4: Simplify right side
    211.20x = 36,116.85
  5. Step 5: Solve for x
    x = 36,116.85/211.20
  6. Step 6: Final answer
    x = 171.01

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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.