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Finding the Fourth Proportional to 210.68, 316.05 and 128.56

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Solution

The fourth proportional to 210.68, 316.05 and 128.56 is: 192.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    210.68 : 316.05 = 128.56 : x
  2. Step 2: Convert to fraction form
    210.68/316.05 = 128.56/x
  3. Step 3: Cross multiply
    210.68x = 316.05 × 128.56
  4. Step 4: Simplify right side
    210.68x = 40,631.39
  5. Step 5: Solve for x
    x = 40,631.39/210.68
  6. Step 6: Final answer
    x = 192.86

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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.