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Finding the Fourth Proportional to 693.78, 957.40 and 399.21

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Solution

The fourth proportional to 693.78, 957.40 and 399.21 is: 550.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    693.78 : 957.40 = 399.21 : x
  2. Step 2: Convert to fraction form
    693.78/957.40 = 399.21/x
  3. Step 3: Cross multiply
    693.78x = 957.40 × 399.21
  4. Step 4: Simplify right side
    693.78x = 382,206.70
  5. Step 5: Solve for x
    x = 382,206.70/693.78
  6. Step 6: Final answer
    x = 550.90

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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.