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Finding the Fourth Proportional to 684.72, 944.90 and 390

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Solution

The fourth proportional to 684.72, 944.90 and 390 is: 538.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    684.72 : 944.90 = 390 : x
  2. Step 2: Convert to fraction form
    684.72/944.90 = 390/x
  3. Step 3: Cross multiply
    684.72x = 944.90 × 390
  4. Step 4: Simplify right side
    684.72x = 368,511
  5. Step 5: Solve for x
    x = 368,511/684.72
  6. Step 6: Final answer
    x = 538.19

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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.