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Finding the Third Proportional to 390.94 and 618.38

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Solution

The third proportional to 390.94 and 618.38 is: 978.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.94 : 618.38 = 618.38 : x
  2. Step 2: Convert to fraction form
    390.94/618.38 = 618.38/x
  3. Step 3: Cross multiply
    390.94x = 618.38 × 618.38
  4. Step 4: Simplify right side
    390.94x = 382,387.64
  5. Step 5: Solve for x
    x = 382,387.64/390.94
  6. Step 6: Final answer
    x = 978.13

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Why These Related Problems?

These problems maintain the same ratio (1.58) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.