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Finding the Third Proportional to 987 and 1,428.75

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Solution

The third proportional to 987 and 1,428.75 is: 2,068.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    987 : 1,428.75 = 1,428.75 : x
  2. Step 2: Convert to fraction form
    987/1,428.75 = 1,428.75/x
  3. Step 3: Cross multiply
    987x = 1,428.75 × 1,428.75
  4. Step 4: Simplify right side
    987x = 2,041,326.56
  5. Step 5: Solve for x
    x = 2,041,326.56/987
  6. Step 6: Final answer
    x = 2,068.21

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Why These Related Problems?

These problems maintain the same ratio (1.45) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.