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Finding the Fourth Proportional to 390.98, 539.02 and 312.56

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Solution

The fourth proportional to 390.98, 539.02 and 312.56 is: 430.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.98 : 539.02 = 312.56 : x
  2. Step 2: Convert to fraction form
    390.98/539.02 = 312.56/x
  3. Step 3: Cross multiply
    390.98x = 539.02 × 312.56
  4. Step 4: Simplify right side
    390.98x = 168,476.66
  5. Step 5: Solve for x
    x = 168,476.66/390.98
  6. Step 6: Final answer
    x = 430.91

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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.