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Finding the Fourth Proportional to 220.40, 330.78 and 139.28

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Solution

The fourth proportional to 220.40, 330.78 and 139.28 is: 209.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    220.40 : 330.78 = 139.28 : x
  2. Step 2: Convert to fraction form
    220.40/330.78 = 139.28/x
  3. Step 3: Cross multiply
    220.40x = 330.78 × 139.28
  4. Step 4: Simplify right side
    220.40x = 46,071.04
  5. Step 5: Solve for x
    x = 46,071.04/220.40
  6. Step 6: Final answer
    x = 209.03

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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.