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Finding the Fourth Proportional to 212.35, 318.60 and 90.70

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Solution

The fourth proportional to 212.35, 318.60 and 90.70 is: 136.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.35 : 318.60 = 90.70 : x
  2. Step 2: Convert to fraction form
    212.35/318.60 = 90.70/x
  3. Step 3: Cross multiply
    212.35x = 318.60 × 90.70
  4. Step 4: Simplify right side
    212.35x = 28,897.02
  5. Step 5: Solve for x
    x = 28,897.02/212.35
  6. Step 6: Final answer
    x = 136.08

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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.