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Finding the Fourth Proportional to 212.55, 318.75 and 90.82

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Solution

The fourth proportional to 212.55, 318.75 and 90.82 is: 136.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.55 : 318.75 = 90.82 : x
  2. Step 2: Convert to fraction form
    212.55/318.75 = 90.82/x
  3. Step 3: Cross multiply
    212.55x = 318.75 × 90.82
  4. Step 4: Simplify right side
    212.55x = 28,948.88
  5. Step 5: Solve for x
    x = 28,948.88/212.55
  6. Step 6: Final answer
    x = 136.20

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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.