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Finding the Fourth Proportional to 212.16, 292.80 and 128.16

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Solution

The fourth proportional to 212.16, 292.80 and 128.16 is: 176.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.16 : 292.80 = 128.16 : x
  2. Step 2: Convert to fraction form
    212.16/292.80 = 128.16/x
  3. Step 3: Cross multiply
    212.16x = 292.80 × 128.16
  4. Step 4: Simplify right side
    212.16x = 37,525.25
  5. Step 5: Solve for x
    x = 37,525.25/212.16
  6. Step 6: Final answer
    x = 176.87

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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.