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Finding the Fourth Proportional to 211.99, 318.12 and 90.31

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Solution

The fourth proportional to 211.99, 318.12 and 90.31 is: 135.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.99 : 318.12 = 90.31 : x
  2. Step 2: Convert to fraction form
    211.99/318.12 = 90.31/x
  3. Step 3: Cross multiply
    211.99x = 318.12 × 90.31
  4. Step 4: Simplify right side
    211.99x = 28,729.42
  5. Step 5: Solve for x
    x = 28,729.42/211.99
  6. Step 6: Final answer
    x = 135.52

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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.