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Finding the Fourth Proportional to 211.20, 316.59 and 66.81

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Solution

The fourth proportional to 211.20, 316.59 and 66.81 is: 100.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.20 : 316.59 = 66.81 : x
  2. Step 2: Convert to fraction form
    211.20/316.59 = 66.81/x
  3. Step 3: Cross multiply
    211.20x = 316.59 × 66.81
  4. Step 4: Simplify right side
    211.20x = 21,151.38
  5. Step 5: Solve for x
    x = 21,151.38/211.20
  6. Step 6: Final answer
    x = 100.15

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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.