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Finding the Fourth Proportional to 216, 298.08 and 128.72

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Solution

The fourth proportional to 216, 298.08 and 128.72 is: 177.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    216 : 298.08 = 128.72 : x
  2. Step 2: Convert to fraction form
    216/298.08 = 128.72/x
  3. Step 3: Cross multiply
    216x = 298.08 × 128.72
  4. Step 4: Simplify right side
    216x = 38,369.60
  5. Step 5: Solve for x
    x = 38,369.60/216
  6. Step 6: Final answer
    x = 177.64

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.