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Finding the Fourth Proportional to 211.16, 316.78 and 66.85

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Solution

The fourth proportional to 211.16, 316.78 and 66.85 is: 100.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.16 : 316.78 = 66.85 : x
  2. Step 2: Convert to fraction form
    211.16/316.78 = 66.85/x
  3. Step 3: Cross multiply
    211.16x = 316.78 × 66.85
  4. Step 4: Simplify right side
    211.16x = 21,175.78
  5. Step 5: Solve for x
    x = 21,175.78/211.16
  6. Step 6: Final answer
    x = 100.28

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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.