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Finding the Third Proportional to 978.75 and 1,391.63

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Solution

The third proportional to 978.75 and 1,391.63 is: 1,978.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.75 : 1,391.63 = 1,391.63 : x
  2. Step 2: Convert to fraction form
    978.75/1,391.63 = 1,391.63/x
  3. Step 3: Cross multiply
    978.75x = 1,391.63 × 1,391.63
  4. Step 4: Simplify right side
    978.75x = 1,936,620.14
  5. Step 5: Solve for x
    x = 1,936,620.14/978.75
  6. Step 6: Final answer
    x = 1,978.67

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These problems maintain the same ratio (1.42) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.