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Finding the Fourth Proportional to 390.80, 539.40 and 235.60

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Solution

The fourth proportional to 390.80, 539.40 and 235.60 is: 325.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.80 : 539.40 = 235.60 : x
  2. Step 2: Convert to fraction form
    390.80/539.40 = 235.60/x
  3. Step 3: Cross multiply
    390.80x = 539.40 × 235.60
  4. Step 4: Simplify right side
    390.80x = 127,082.64
  5. Step 5: Solve for x
    x = 127,082.64/390.80
  6. Step 6: Final answer
    x = 325.19

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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.