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Finding the Third Proportional to 420.19 and 989.72

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Solution

The third proportional to 420.19 and 989.72 is: 2,331.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.19 : 989.72 = 989.72 : x
  2. Step 2: Convert to fraction form
    420.19/989.72 = 989.72/x
  3. Step 3: Cross multiply
    420.19x = 989.72 × 989.72
  4. Step 4: Simplify right side
    420.19x = 979,543.20
  5. Step 5: Solve for x
    x = 979,543.20/420.19
  6. Step 6: Final answer
    x = 2,331.21

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Why These Related Problems?

These problems maintain the same ratio (2.36) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.