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Finding the Fourth Proportional to 218.72, 328.08 and 90.48

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Solution

The fourth proportional to 218.72, 328.08 and 90.48 is: 135.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    218.72 : 328.08 = 90.48 : x
  2. Step 2: Convert to fraction form
    218.72/328.08 = 90.48/x
  3. Step 3: Cross multiply
    218.72x = 328.08 × 90.48
  4. Step 4: Simplify right side
    218.72x = 29,684.68
  5. Step 5: Solve for x
    x = 29,684.68/218.72
  6. Step 6: Final answer
    x = 135.72

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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.