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Finding the Fourth Proportional to 661, 912.30 and 385

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Solution

The fourth proportional to 661, 912.30 and 385 is: 531.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    661 : 912.30 = 385 : x
  2. Step 2: Convert to fraction form
    661/912.30 = 385/x
  3. Step 3: Cross multiply
    661x = 912.30 × 385
  4. Step 4: Simplify right side
    661x = 351,235.50
  5. Step 5: Solve for x
    x = 351,235.50/661
  6. Step 6: Final answer
    x = 531.37

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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.