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Finding the Fourth Proportional to 407.80, 611.70 and 393.40

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Solution

The fourth proportional to 407.80, 611.70 and 393.40 is: 590.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    407.80 : 611.70 = 393.40 : x
  2. Step 2: Convert to fraction form
    407.80/611.70 = 393.40/x
  3. Step 3: Cross multiply
    407.80x = 611.70 × 393.40
  4. Step 4: Simplify right side
    407.80x = 240,642.78
  5. Step 5: Solve for x
    x = 240,642.78/407.80
  6. Step 6: Final answer
    x = 590.10

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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.