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Finding the Third Proportional to 390 and 618

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Solution

The third proportional to 390 and 618 is: 979.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    390 : 618 = 618 : x
  2. Step 2: Convert to fraction form
    390/618 = 618/x
  3. Step 3: Cross multiply
    390x = 618 × 618
  4. Step 4: Simplify right side
    390x = 381,924
  5. Step 5: Solve for x
    x = 381,924/390
  6. Step 6: Final answer
    x = 979.29

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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.