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Finding the Fourth Proportional to 212.15, 318.30 and 90.42

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Solution

The fourth proportional to 212.15, 318.30 and 90.42 is: 135.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.15 : 318.30 = 90.42 : x
  2. Step 2: Convert to fraction form
    212.15/318.30 = 90.42/x
  3. Step 3: Cross multiply
    212.15x = 318.30 × 90.42
  4. Step 4: Simplify right side
    212.15x = 28,779.15
  5. Step 5: Solve for x
    x = 28,779.15/212.15
  6. Step 6: Final answer
    x = 135.65

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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.