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Finding the Fourth Proportional to 212.64, 318.72 and 90.84

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Solution

The fourth proportional to 212.64, 318.72 and 90.84 is: 136.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.64 : 318.72 = 90.84 : x
  2. Step 2: Convert to fraction form
    212.64/318.72 = 90.84/x
  3. Step 3: Cross multiply
    212.64x = 318.72 × 90.84
  4. Step 4: Simplify right side
    212.64x = 28,952.52
  5. Step 5: Solve for x
    x = 28,952.52/212.64
  6. Step 6: Final answer
    x = 136.16

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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.