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Finding the Fourth Proportional to 823.50, 1,235.64 and 390.42

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Solution

The fourth proportional to 823.50, 1,235.64 and 390.42 is: 585.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    823.50 : 1,235.64 = 390.42 : x
  2. Step 2: Convert to fraction form
    823.50/1,235.64 = 390.42/x
  3. Step 3: Cross multiply
    823.50x = 1,235.64 × 390.42
  4. Step 4: Simplify right side
    823.50x = 482,418.57
  5. Step 5: Solve for x
    x = 482,418.57/823.50
  6. Step 6: Final answer
    x = 585.81

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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.