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Finding the Fourth Proportional to 212.68, 318.78 and 84.28

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Solution

The fourth proportional to 212.68, 318.78 and 84.28 is: 126.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.68 : 318.78 = 84.28 : x
  2. Step 2: Convert to fraction form
    212.68/318.78 = 84.28/x
  3. Step 3: Cross multiply
    212.68x = 318.78 × 84.28
  4. Step 4: Simplify right side
    212.68x = 26,866.78
  5. Step 5: Solve for x
    x = 26,866.78/212.68
  6. Step 6: Final answer
    x = 126.32

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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.