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Finding the Third Proportional to 428 and 689.25

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Solution

The third proportional to 428 and 689.25 is: 1,109.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    428 : 689.25 = 689.25 : x
  2. Step 2: Convert to fraction form
    428/689.25 = 689.25/x
  3. Step 3: Cross multiply
    428x = 689.25 × 689.25
  4. Step 4: Simplify right side
    428x = 475,065.56
  5. Step 5: Solve for x
    x = 475,065.56/428
  6. Step 6: Final answer
    x = 1,109.97

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Why These Related Problems?

These problems maintain the same ratio (1.61) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.