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Finding the Fourth Proportional to 390.80, 539.30 and 235.55

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Solution

The fourth proportional to 390.80, 539.30 and 235.55 is: 325.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.80 : 539.30 = 235.55 : x
  2. Step 2: Convert to fraction form
    390.80/539.30 = 235.55/x
  3. Step 3: Cross multiply
    390.80x = 539.30 × 235.55
  4. Step 4: Simplify right side
    390.80x = 127,034.05
  5. Step 5: Solve for x
    x = 127,034.05/390.80
  6. Step 6: Final answer
    x = 325.06

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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.