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Finding the Fourth Proportional to 312.40, 431.28 and 219.28

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Solution

The fourth proportional to 312.40, 431.28 and 219.28 is: 302.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.40 : 431.28 = 219.28 : x
  2. Step 2: Convert to fraction form
    312.40/431.28 = 219.28/x
  3. Step 3: Cross multiply
    312.40x = 431.28 × 219.28
  4. Step 4: Simplify right side
    312.40x = 94,571.08
  5. Step 5: Solve for x
    x = 94,571.08/312.40
  6. Step 6: Final answer
    x = 302.72

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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.