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Finding the Fourth Proportional to 210.18, 314.81 and 128.78

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Solution

The fourth proportional to 210.18, 314.81 and 128.78 is: 192.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    210.18 : 314.81 = 128.78 : x
  2. Step 2: Convert to fraction form
    210.18/314.81 = 128.78/x
  3. Step 3: Cross multiply
    210.18x = 314.81 × 128.78
  4. Step 4: Simplify right side
    210.18x = 40,539.01
  5. Step 5: Solve for x
    x = 40,539.01/210.18
  6. Step 6: Final answer
    x = 192.88

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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.